AC won't take freon (1 Viewer)

[SeanLX]

So my used compressor locked up. I installed a new Denso compressor, Denso receiver dryer, new (non oem) expansion valve.

I get everything buttoned up, pull a vacuum and it looks good to go. Hook the can up to the gauges, start it up with the AC on high and it didn't go as planned.

The clutch engaged and it started taking 134a. Can got cold but it only took about 1/4 of the first can. The low side pressure went really high and the high side pressure was the same as low side.

Now I'm trying to figure out if it's a bad new compressor or a problem with the expansion valve.

Any thoughts?

 

[flintknapper]

So my used compressor locked up. I installed a new Denso compressor, Denso receiver dryer, new (non oem) expansion valve.

I get everything buttoned up, pull a vacuum and it looks good to go. Hook the can up to the gauges, start it up with the AC on high and it didn't go as planned.

The clutch engaged and it started taking 134a. Can got cold but it only took about 1/4 of the first can. The low side pressure went really high and the high side pressure was the same as low side.

Now I'm trying to figure out if it's a bad new compressor or a problem with the expansion valve.

Any thoughts?

Well.....we need to know a little more about the 'procedure' you used.

Did your new compressor come 'pre-oiled' or did you have to 'add' oil and now much of what type?

You pulled a vacuum (as you should). For how long? What what was the reading on the gauge and did it HOLD a vacuum (no leaks) for at least 15 minutes with no appreciable change of the gauge reading?

Sounds like you attempted to 'Vapor Charge' the system right from the start (not my favorite method by a long shot). We need to know what valves you had opened and which were shut when you charged the system and also when you took the gauge readings. IF you are reading the low side pressure with the valve open (it should be closed) then of course you are going to see a high pressure reading. Close the low side valve and let the system stabilize 5-10 minutes.

When charging a system....I like to 'pre-charge' it with the first can (if using small cans) as a liquid...into the high side...into the vacuum (engine and compressor NOT running).

This insures there is refrigerant in the system upon start up that will carry the oil/lubricant through the system. The oil will not move well on its own. Also, you will have enough refrigerant/pressure in the system (upon start up) that the clutch will engage (but not cycle)....providing immediate lubrication and suction to take in the 'Vapor Charge' into the low side port as you finish the charging procedure.

I can't say what the condition of your compressor is at this juncture....until you tell us how you had the valves set and how much of a refrigerant charge you think the system might have taken. If you had certain valves open when charging or reading the pressure that might account for the high pressure reading AND the pressures reading the same on both the high and low sides.

If it was done correctly...then I can only say this: IF you have sufficient charge, (engine running about 1000-1500 RPM), compressor engaged and clutch turning, ALL manifold valves closed and the pressures still read the same..... the compressor is knackered.

 

[mingles]

So my used compressor locked up. I installed a new Denso compressor, Denso receiver dryer, new (non oem) expansion valve.

I get everything buttoned up, pull a vacuum and it looks good to go. Hook the can up to the gauges, start it up with the AC on high and it didn't go as planned.

The clutch engaged and it started taking 134a. Can got cold but it only took about 1/4 of the first can. The low side pressure went really high and the high side pressure was the same as low side.

Now I'm trying to figure out if it's a bad new compressor or a problem with the expansion valve.

Any thoughts?

I did the same replacement and recharge two years ago on my LX. It was my first time doing this and I followed the FSM procedure exactly and it worked fine. My memory is fuzzy but I do recall that I had to spread the process out over a few hours as the cans would ice up and not be drawn into the system.

I don't have access to my FSM now but IIRC there is a good troubleshooting section in there for the process.

 

[Hornd]

You jumped the low pressure switch?

 

[SeanLX]

Well.....we need to know a little more about the 'procedure' you used.

Did your new compressor come 'pre-oiled' or did you have to 'add' oil and now much of what type?

You pulled a vacuum (as you should). For how long? What what was the reading on the gauge and did it HOLD a vacuum (no leaks) for at least 15 minutes with no appreciable change of the gauge reading?

Sounds like you attempted to 'Vapor Charge' the system right from the start (not my favorite method by a long shot). We need to know what valves you had opened and which were shut when you charged the system and also when you took the gauge readings. IF you are reading the low side pressure with the valve open (it should be closed) then of course you are going to see a high pressure reading. Close the low side valve and let the system stabilize 5-10 minutes.

When charging a system....I like to 'pre-charge' it with the first can (if using small cans) as a liquid...into the high side...into the vacuum (engine and compressor NOT running).

This insures there is refrigerant in the system upon start up that will carry the oil/lubricant through the system. The oil will not move well on its own. Also, you will have enough refrigerant/pressure in the system (upon start up) that the clutch will engage (but not cycle)....providing immediate lubrication and suction to take in the 'Vapor Charge' into the low side port as you finish the charging procedure.

I can't say what the condition of your compressor is at this juncture....until you tell us how you had the valves set and how much of a refrigerant charge you think the system might have taken. If you had certain valves open when charging or reading the pressure that might account for the high pressure reading AND the pressures reading the same on both the high and low sides.

If it was done correctly...then I can only say this: IF you have sufficient charge, (engine running about 1000-1500 RPM), compressor engaged and clutch turning, ALL manifold valves closed and the pressures still read the same..... the compressor is knackered.

The new Denso compressor was pre-oiled. I poured it out to check the volume and put it back where it came from. Seemed OK.

I pulled a vacuum for 1/2 hour+. The Harbor Freight gauges aren't very accurate but it held the same 25+ it read while hooked up for another 1/2 hour.

I had not heard of pre-charging the high side. I like that and will from now on.

I did not have to jump the low pressure switch. I hooked it up, no clutch engagement so I was looking for the sensor to jump and decided to turn the AC off and back on. It engaged and stayed engaged so I quit looking.

I followed the FSM and only opened the low side knob while the engine was running. ..except for cracking the high side knob for a second after it seemed to quit to see if it was doing anything. It only matched the low side pressure that was really high. Closed it again and kept working with the low side only open.
I think the low side pressure was 70-80psi. It was just what came from the can and I didn't close the valve to check just the system.

as I was shutting down I closed the can before disconnecting so I'm thinking the gauge was reading only what was in the system (80psi ish).

Too high a low side pressure and no extra pressure on the high side makes me thing bad compressor. It seems like the can only put enough to equalize and fill the vacuum in the system.

I'm still hoping I missed something before I go trying to change out the compressor again.

 

[excessive]

It can take a long time for a can to be drawn into an empty system , maybe 15 minutes or so. Turn the can upside downs and shake to help dispense refrigerant .

 

[BILT4ME]

It can take a long time for a can to be drawn into an empty system , maybe 15 minutes or so. Turn the can upside downs and shake to help dispense refrigerant .

You don't want to turn it upside down if the engine and compressor are running. You run the risk of liquid entering the system and locking up the pump.

 

[flintknapper]

The new Denso compressor was pre-oiled. I poured it out to check the volume and put it back where it came from. Seemed OK.

I pulled a vacuum for 1/2 hour+. The Harbor Freight gauges aren't very accurate but it held the same 25+ it read while hooked up for another 1/2 hour.

I had not heard of pre-charging the high side. I like that and will from now on.

I did not have to jump the low pressure switch. I hooked it up, no clutch engagement so I was looking for the sensor to jump and decided to turn the AC off and back on. It engaged and stayed engaged so I quit looking.

I followed the FSM and only opened the low side knob while the engine was running. ..except for cracking the high side knob for a second after it seemed to quit to see if it was doing anything. It only matched the low side pressure that was really high. Closed it again and kept working with the low side only open.
I think the low side pressure was 70-80psi. It was just what came from the can and I didn't close the valve to check just the system.

as I was shutting down I closed the can before disconnecting so I'm thinking the gauge was reading only what was in the system (80psi ish).

Too high a low side pressure and no extra pressure on the high side makes me thing bad compressor. It seems like the can only put enough to equalize and fill the vacuum in the system.

I'm still hoping I missed something before I go trying to change out the compressor again.

You say your old compressor 'locked up'? When you removed the expansion valve from the evaporator, did you notice any metal particles in the prescreen? IF it was clean....then normally I will just flush the system (hoses, condenser and evaporator) blow it out real good, install a new TXV and Drier. Install new O-rings and then pump it down. BUT if there was evidence of metal particles it is best to replace the Condenser and Evaporator or you risk having metal shavings/particles go through your new compressor and it will be short lived.

But lets assume all is well. Your low side pressure reading 70-80 psi (with low side valve open) is NOT high...depending upon the ambient temperature. If it was 80° f outside when you were doing this...then the refrigerant pressure alone was about 85 psi. So this might be the reason your A/C clutch engaged without you needing to jump the pressure switch.

At this point....I would reconnect the gauges (all valves shut) and see what your pressures are (high and low side, engine on, a/c on high, rpm about 1200). Let us know what you get and also note if the gauge needles flutter any.

I'm thinking you read the low side pressure with the valve open and got spooked at what you saw. If you then shut everything down and turned off the valves the system will 'equalize' (if not obstructed)...which is normal (low side and high side will read the same, engine off, a/c off).

You might end up needing to evacuate the system, pump it back down, pre-charge and then finish Vapor filling from the low side port, depending upon what you come back with.

 

[lumbee1]

Hey Sean, check your hoses! The cheaper manifold gauge set have awful o-rings that when compressed will block the hose. I had the exact same problem as you and spent DAYS looking at it. I thought I was doing something wrong. I eventually had Eric Johnston look at it. He pulled the hose apart and found one of the o-rings completely flat and blocking the port. We trimmed out the inside of the o-ring and added freon with no problem.

 

[flintknapper]

You don't want to turn it upside down if the engine and compressor are running. You run the risk of liquid entering the system and locking up the pump.

^^^^^^^^ Correct.

You can often get away with tilting it slightly onto its side or just shaking the can a bit (while watching the gauge) to get things flowing again, but I agree......I don't recommend doing that if you are a novice at A/C.

 

[lumbee1]

BTW, I installed a new Denso compressor, ebay dryer, and an ebay expansion valve. I purchased two large cans and used every bit of them. My compressor came pre-oiled and didn't need anything added. My sight glass shows that I still have some air in the system but the AC works great.

 

[flintknapper]

Hey Sean, check your hoses! The cheaper manifold gauge set have awful o-rings that when compressed will block the hose. I had the exact same problem as you and spent DAYS looking at it. I thought I was doing something wrong. I eventually had Eric Johnston look at it. He pulled the hose apart and found one of the o-rings completely flat and blocking the port. We trimmed out the inside of the o-ring and added freon with no problem.

Yes, excellent suggestion. IF the fittings are over-tightened, the cheaper ones can absolutely block the hose. Good way to avoid that is to purge each hose at one fitting (back it off just enough to let a refrigerant escape and then tighten it back up only enough to stop the flow). You want to always purge the lines of air anyway.

 

[SeanLX]

I'm used to it taking a while to fill but I might have gotten a little spooked. I shook the can but didn't turn it upside down (scared of putting in liquid).

It took 20+ minutes for about a 1/4 can where the bottom of the can frosted up. After that the can warmed up and didn't seem to take any more.

I'll check the hoses/gauges tonight and try it again starting with both closed to read pressure. I might pull the vacuum again and try to fill the high side first. It really didn't take much last night so there's not much in there to loose.

Thanks and I'll make sure to update after I try again tonight.

 

[flintknapper]

I'm used to it taking a while to fill but I might have gotten a little spooked. I shook the can but didn't turn it upside down (scared of putting in liquid).

It took 20+ minutes for about a 1/4 can where the bottom of the can frosted up. After that the can warmed up and didn't seem to take any more.

I'll check the hoses/gauges tonight and try it again starting with both closed. I might pull the vacuum again and try to fill the high side first. It really didn't take much last night so there's not much in there to loose.

Thanks and I'll make sure to update after I try again tonight.

Sounds good, hopefully just something simple.

 

[BILT4ME]

I have actually set the can of freon in a bowl of HOT water in order to offset the freezing up issues. Many times, the "experts will set the cans in the sun to "preheat" them before they start.

 

[SeanLX]

It's Alive!

I guess I did just get spooked by the high number with the low pressure knob open and how slow it was taking a charge.

Last night I pulled a vacuum again, then dumped a can into the high side (engine off). That went in much better than I expected.
Then started it up and the clutch kicked in immediately. Hooked up the second can and waited. Cold air out of the vents!
Finished that can off in some hot water and put in a little of a 3rd can to meet the 30 oz. spec in the FSM. (12 oz. cans)

~68° outside. 28 low side and 225 high side with steady needles. 42° from the vents. I'll take it.

Thanks for all the advice and hopefully it will be cooling for a long time.

 

[flintknapper]

It's Alive!

I guess I did just get spooked by the high number with the low pressure knob open and how slow it was taking a charge.

Last night I pulled a vacuum again, then dumped a can into the high side (engine off). That went in much better than I expected.
Then started it up and the clutch kicked in immediately. Hooked up the second can and waited. Cold air out of the vents!
Finished that can off in some hot water and put in a little of a 3rd can to meet the 30 oz. spec in the FSM. (12 oz. cans)

~68° outside. 28 low side and 225 high side with steady needles. 42° from the vents. I'll take it.

Thanks for all the advice and hopefully it will be cooling for a long time.

Good job Sean!

Sounds like you are set. And I hope you know....you did the RIGHT thing to stop when you did....(if you suspect any problem whatsoever).

I think you were just seeing what would seem like 'high pressure' on the low side (which was just can pressure) and the high side was not yet reading a higher number because there wasn't yet a sufficient charge, so both sides looked to be the same pressure (a potentially bad sign).

So....now you know where the error was, you corrected it and are knowledgeable in case you ever need to do it again.

 

[Aloha Jen]

You say your old compressor 'locked up'? When you removed the expansion valve from the evaporator, did you notice any metal particles in the prescreen? IF it was clean....then normally I will just flush the system (hoses, condenser and evaporator) blow it out real good, install a new TXV and Drier. Install new O-rings and then pump it down. BUT if there was evidence of metal particles it is best to replace the Condenser and Evaporator or you risk having metal shavings/particles go through your new compressor and it will be short lived.

But lets assume all is well. Your low side pressure reading 70-80 psi (with low side valve open) is NOT high...depending upon the ambient temperature. If it was 80° f outside when you were doing this...then the refrigerant pressure alone was about 85 psi. So this might be the reason your A/C clutch engaged without you needing to jump the pressure switch.

At this point....I would reconnect the gauges (all valves shut) and see what your pressures are (high and low side, engine on, a/c on high, rpm about 1200). Let us know what you get and also note if the gauge needles flutter any.

I'm thinking you read the low side pressure with the valve open and got spooked at what you saw. If you then shut everything down and turned off the valves the system will 'equalize' (if not obstructed)...which is normal (low side and high side will read the same, engine off, a/c off).

You might end up needing to evacuate the system, pump it back down, pre-charge and then finish Vapor filling from the low side port, depending upon what you come back with.

I know it's an old post, but we are filling our AC as we speak and are having similar problems the original poster was having. Here is what is happening:
Followed you directions and pre charged the high side with one can as liquid with engine off and low side closed. High side gauge went to 100 psi after one can in. Waited a bit, about 10 mins. Then started engine, revved to 1500 rpm, blasted AC on high. But no clutch engaged. Began filling low side with new can as vapor, with hi side closed. After started filling, low side gauge shot up to 98 psi and Mike closed low side gauge. But still no clutch engaged. High side stayed at 100 psi. Mike decided to jump the clutch with wire straight from battery to test clutch/compressor, and clutch immediatly engaged. Low side gauge stayed at around 100 psi, while hi side gauge went to 205 psi while clutch was jumped. Also, when clutch was jumped/engaged, I measured temps at vents and temps dropped from 90 to 70 degrees. When Mike disengaged clutch, psi on hi side began to drop and temps went back up at vents. When jumping the clutch again, same thing happened....so this means the compressor and clutch are working and cooling right? However after a few cycles hot wiring engaging and disengaging the clutch, we turned engine off and gauges settled at 100 psi on the low side and 110 psi on the hi side. After 20 mins of waiting, gauges read like this still:

After another 20 mins, the gauges read the same on both sides as the above photo, so looks like they have settled like that.
My questions are, why is the clutch not engaging? Does it just not have enough freon charged in it yet? Mike is a bit nervous about adding more to the low side because the psi is at 96, and the fsm says to try not to exceed 60 psi when filling on low side. Ambient temp is about 88 degrees. Should we just keep filling on the low side until clutch engages on its own? What are good psi's to not exceed while we are filling on low side with engine on? Any help would be greatly appreciated!!

 

[White Stripe]

I know it's an old post, but we are filling our AC as we speak and are having similar problems the original poster was having. Here is what is happening:
Followed you directions and pre charged the high side with one can as liquid with engine off and low side closed. High side gauge went to 100 psi after one can in. Waited a bit, about 10 mins. Then started engine, revved to 1500 rpm, blasted AC on high. But no clutch engaged. Began filling low side with new can as vapor, with hi side closed. After started filling, low side gauge shot up to 98 psi and Mike closed low side gauge. But still no clutch engaged. High side stayed at 100 psi. Mike decided to jump the clutch with wire straight from battery to test clutch/compressor, and clutch immediatly engaged. Low side gauge stayed at around 100 psi, while hi side gauge went to 205 psi while clutch was jumped. Also, when clutch was jumped/engaged, I measured temps at vents and temps dropped from 90 to 70 degrees. When Mike disengaged clutch, psi on hi side began to drop and temps went back up at vents. When jumping the clutch again, same thing happened....so this means the compressor and clutch are working and cooling right? However after a few cycles hot wiring engaging and disengaging the clutch, we turned engine off and gauges settled at 100 psi on the low side and 110 psi on the hi side. After 20 mins of waiting, gauges read like this still:
View attachment 1465781
After another 20 mins, the gauges read the same on both sides as the above photo, so looks like they have settled like that.
My questions are, why is the clutch not engaging? Does it just not have enough freon charged in it yet? Mike is a bit nervous about adding more to the low side because the psi is at 96, and the fsm says to try not to exceed 60 psi when filling on low side. Ambient temp is about 88 degrees. Should we just keep filling on the low side until clutch engages on its own? What are good psi's to not exceed while we are filling on low side with engine on? Any help would be greatly appreciated!!

I really don't recommend charging it with cans. It's very easy to overcharge and difficult to get the correct charge amount. Just a little overcharging will lower the systems efficiency and you won't get maximum cooling potential. Looking at your gauges with the system off it would seem you have overcharged it. That being the case the system should operate. Turn key on engine off push ac button on. Check for power at your fuse and Chek the fuse. If that's good, Check for power going into and out of the pressure switch with a test light or volt meter. If you don't have power to your pressure switch, the ac switch on the dash may be bad. If you have power into the pressure switch but not out of, you may have a bad pressure switch. I would especially suspect any parts that are old or used and one of them will likely be the culprit.

 

[flintknapper]

I know it's an old post, but we are filling our AC as we speak and are having similar problems the original poster was having. Here is what is happening:
Followed you directions and pre charged the high side with one can as liquid with engine off and low side closed. High side gauge went to 100 psi after one can in. Waited a bit, about 10 mins. Then started engine, revved to 1500 rpm, blasted AC on high. But no clutch engaged. Began filling low side with new can as vapor, with hi side closed. After started filling, low side gauge shot up to 98 psi and Mike closed low side gauge. But still no clutch engaged. High side stayed at 100 psi. Mike decided to jump the clutch with wire straight from battery to test clutch/compressor, and clutch immediatly engaged. Low side gauge stayed at around 100 psi, while hi side gauge went to 205 psi while clutch was jumped. Also, when clutch was jumped/engaged, I measured temps at vents and temps dropped from 90 to 70 degrees. When Mike disengaged clutch, psi on hi side began to drop and temps went back up at vents. When jumping the clutch again, same thing happened....so this means the compressor and clutch are working and cooling right? However after a few cycles hot wiring engaging and disengaging the clutch, we turned engine off and gauges settled at 100 psi on the low side and 110 psi on the hi side. After 20 mins of waiting, gauges read like this still:
After another 20 mins, the gauges read the same on both sides as the above photo, so looks like they have settled like that.
My questions are, why is the clutch not engaging? Does it just not have enough freon charged in it yet? Mike is a bit nervous about adding more to the low side because the psi is at 96, and the fsm says to try not to exceed 60 psi when filling on low side. Ambient temp is about 88 degrees. Should we just keep filling on the low side until clutch engages on its own? What are good psi's to not exceed while we are filling on low side with engine on? Any help would be greatly appreciated!!

Jen, with the engine off (compressor not turning) you are looking at the 'static' pressure on your gauges. The system will equalize and the readings on both gauges will be roughly the same. The static pressure for 134a at the ambient you cited (88° F.) would be about what your gauges are showing (96 psi). Don't worry yourself with that.

The static pressure is a mostly useless figure EXCEPT to show you have some amount of liquid refrigerant in the system. It does NOT indicate how much is in the system. Static pressure will be the same if you had one drop of liquid refrigerant in the system or two pounds. So don't be concerned with that.

Let's move on. It will be pointless to continue until you find the reason the compressor clutch is not engaging. You have already introduced one can (some amount of weight? into the system) and you have almost 100 psi static pressure, so we know that is enough to activate the pressure switch (if it is not faulty).

Let's turn our attention to tracing the electrical circuit and see IF you have power (12 volts) getting to the compressor clutch.

You'll want to check the easy stuff first (fuses), then dash switches, wiring. But we have to settle that issue before moving forward. Once we have the electrical system calling for the compressor clutch to engage...we can go back to the charging phase. You have plenty of static pressure...so DON'T add more refrigerant at this juncture.

Let us know what you find.

Flint.