AC cooling woes

[TXMeatball]

Just replaced the compressor, condenser, evaporator, drier, and expansion valve on my 97 LC. Vacuumed it for 2 hours, weighed around 1.8lbs of 134a with a little extra to compensate for the manifold/lines. Pressures were about 20-22ish on the low side and 220-30ish on the high.
Got in it after and was super disappointed. Cool, but not cold. My 97 LX parked next to it puts out 65 degrees, the LC puts out 75.
What else causes ACs to suck on 80s? The LC has a blue hub fan clutch (unknown age) and intact fan shroud. I noticed the little ceramic thing that’s on the climate box was dusty so blew that off when I had the evaporator out. Also replaced all the foam seals on the box when it was out too.

 

[Fj80oregon]

That’s odd I just re did my system and get 46 degrees out of the vents idling in 79 degree weather. Assuming you’re watching the clutch engage?

 

[TXMeatball]

That’s odd I just re did my system and get 46 degrees out of the vents idling in 79 degree weather. Assuming you’re watching the clutch engage?

Yep, clutch is working

 

[Irish Reiver]

I finished off my AC just before my road trip in June. Couldn't believe how good it worked. 96f outside and 52f out of the vents - hard to complain about those numbers.

What was your ambient temperature when you measured the pressures? The low and high pressures don't line up in my mind. Did you have good airflow through the condenser when you measured everything? Have you taken it for a drive to do a real world test?

 

[Old Nick]

Just replaced the compressor, condenser, evaporator, drier, and expansion valve on my 97 LC. Vacuumed it for 2 hours, weighed around 1.8lbs of 134a with a little extra to compensate for the manifold/lines. Pressures were about 20-22ish on the low side and 220-30ish on the high.
Got in it after and was super disappointed. Cool, but not cold. My 97 LX parked next to it puts out 65 degrees, the LC puts out 75.
What else causes ACs to suck on 80s? The LC has a blue hub fan clutch (unknown age) and intact fan shroud. I noticed the little ceramic thing that’s on the climate box was dusty so blew that off when I had the evaporator out. Also replaced all the foam seals on the box when it was out too.

Is it holding pressure? I recharged the ac in my wife’s 80. As I did so, a leak became obvious at the firewall (not from o-ring failure), but from a pinhole in the line.

Did you change out all of the o-rings at the union points?

 

[FIDO96]

TX. PM me. I’m in Dallas. Just had my 97 serviced. I’m getting 46 in the vents.

 

[Gascan]

What was your ambient temperature when you measured the pressures? The low and high pressures don't line up in my mind. Did you have good airflow through the condenser when you measured everything? Have you taken it for a drive to do a real world test?

I concur with Irish, the low pressure should be in the high 20's when discharge is 220-230 PSI; something doesn't jive. Please note the ambient air conditions when you remeasure/re-test next time so we can formulate a more detailed picture. How is the blower motor in the LC?

PS: I replace - literally - all of the same A/C components as you just did, in my LX450 back in January 2024, recharged to 32oz, and I've got perfectly cold A/C in hot & humid SW Florida. Sadly, I can't find notes what my pressure read after I recharged the system.

 

[vipergrhd]

This might sound stupid but did you drain the compressor before installing it? Did you add oil to individual parts (Cond,Evap,etc.)?
If your system is (Over) loaded with oil refrigerant won't move as quick into the system. Your gauge readings are good the high side could be a tad lower, you should get below 50*
at 75-80* ambient. Are you running R134A?

 

[TXMeatball]

I finished off my AC just before my road trip in June. Couldn't believe how good it worked. 96f outside and 52f out of the vents - hard to complain about those numbers.
View attachment 3947706
What was your ambient temperature when you measured the pressures? The low and high pressures don't line up in my mind. Did you have good airflow through the condenser when you measured everything? Have you taken it for a drive to do a real world test?

Ambient was 94ish with 40% humidity. I based my pressured off this video: . Airflow was normal for idling.

Is it holding pressure? I recharged the ac in my wife’s 80. As I did so, a leak became obvious at the firewall (not from o-ring failure), but from a pinhole in the line.

Did you change out all of the o-rings at the union points?

No leaks. I let it sit for an hour and the gauge didn't drop. Every single o-ring is new with nylog blue.

I concur with Irish, the low pressure should be in the high 20's when discharge is 220-230 PSI; something doesn't jive. Please note the ambient air conditions when you remeasure/re-test next time so we can formulate a more detailed picture. How is the blower motor in the LC?

PS: I replace - literally - all of the same A/C components as you just did, in my LX450 back in January 2024, recharged to 32oz, and I've got perfectly cold A/C in hot & humid SW Florida. Sadly, I can't find notes what my pressure read after I recharged the system.

Blower motor is fine. Works a lot better now with the new foam actually.

This might sound stupid but did you drain the compressor before installing it? Did you add oil to individual parts (Cond,Evap,etc.)?
If your system is (Over) loaded with oil refrigerant won't move as quick into the system. Your gauge readings are good the high side could be a tad lower, you should get below 50*
at 75-80* ambient. Are you running R134A?

Compressor was pre-filled. Per a thread here I didn't add any additional oil to each part. I believe the entire system holds 8oz? Yes 134a.

 

[Gascan]

Ambient was 94ish with 40% humidity. I based my pressured off this video: . Airflow was normal for idling.

No leaks. I let it sit for an hour and the gauge didn't drop. Every single o-ring is new with nylog blue.

Blower motor is fine. Works a lot better now with the new foam actually.

Compressor was pre-filled. Per a thread here I didn't add any additional oil to each part. I believe the entire system holds 8oz? Yes 134a.

You have all new components that we should assume (for sake of argument) are functioning properly. Your suction (low) side seems a bit low, discharge (high) side is on-point or a hair under and your system underperforming (as evidence by your LX450's A/C output temp). Less someone here has a better suggestion, I'd suggest increasing the charge by up to 4oz (approx. 32oz total) while monitoring the pressures and output temperature. I would increase charge until discharge (high) is sitting at 235 PSI (at 94 degrees ambient) and reassess.

 

[TXMeatball]

Took it for an hour drive. Noticed some things:
Blows colder at idle. Seems like the clutch is kicking off on the highway/at speed. I was toggling the AC on the highway, it would have a lil spurt of cold before going back to mediocre.
Compressor is on at idle. In park I let it rev to 2500 for a minute or two and it stayed on. Fan clutch definitely isn't the culprit, it's moving a ton of air.
Seems to be pointing to low freon?

 

[vipergrhd]

My guess is the system is all backed up with oil, the compressor is trying to push all that oil past through the condenser and going to the evaporator.
Since you didn't know how much oil is in the compressor let's just assume it's for the entire system which could be around 6-7 ounces.
Here is what I usually do on an entire system overhaul, I drain the compressor of the oil it came with while I rotate the clutch to get all the oil out I use the same oil to add it to each component like the condenser and evaporator etc. lets say after that you still have 2-3 ounces left I would only put around 2 ounces of oil on the suction side of the compressor then I would vacuum the system for 2-3 hours or even better overnight then charge the system. I would suggest don't put any extra I would rather be undercharge, I would really prefer using an HVAC machine since it charges the exact amount of refrigerant. Hope this helps in some way.

 

[Gascan]

Took it for an hour drive. Noticed some things:
Blows colder at idle. Seems like the clutch is kicking off on the highway/at speed. I was toggling the AC on the highway, it would have a lil spurt of cold before going back to mediocre.
Compressor is on at idle. In park I let it rev to 2500 for a minute or two and it stayed on. Fan clutch definitely isn't the culprit, it's moving a ton of air.
Seems to be pointing to low freon?

So as not to misunderstand what's going on with your system, I'll simply state that when I had a low charge, my A/C would provide poor cooling at highway speeds and then improve cooling when I'd take an offramp and slow down; but if I stayed unmoving / at idle for a bit longer, cooling would begin to suck again.

 

[LongDuck]

Not to point things in a different direction, but have you checked to be sure your Heater Control Valve is entirely closed? Just a few weeks ago, I checked mine and it was slightly open allowing hot coolant to move through the heater core all the time. This put a thermal load against the A/C, and would increase at higher engine speed as more hot coolant moved under pressure.

It's a quick visual check to see if the valve is closed completely against the metal stop.

 

[TXMeatball]

Alright, getting somewhere. I added a tiny bit (pressure went wack so I immediately stopped), it blows at idle much cooler. Still doing the same thing at speed/RPM. The clutch isn't kicking out. Per the FSM:

At 1500 RPM it's supposed to be 22-36 PSI on the low side. 199-228 PSI on the high. Here's what I'm getting at 1500:

That explains why it's not cooling. The pressure isn't high enough to cut off the compressor.
So where I'm at (could use guidance here).
a. Blockage somewhere (probably expansion valve)? Before I replaced everything I previously had to replace the hard line that runs along the drivers side fender/battery box. At that time I replaced the drier and expansion valve. Took apart the expansion valve to find it clogged with desiccant. I blew out all the lines but didn't find any other desiccant asides from that was at the expansion valve. Taking apart the cooler box again, I didn't see any desiccant this time either. Everything in the system is new now aside from the pressure switch/lines.
b. Excess air/contaminants in system? Not super sure on this, just basing off what the FSM says. Speaking of FSM...

 

[Gascan]

Alright, getting somewhere. I added a tiny bit (pressure went wack so I immediately stopped), it blows at idle much cooler. Still doing the same thing at speed/RPM. The clutch isn't kicking out. Per the FSM:



At 1500 RPM it's supposed to be 22-36 PSI on the low side. 199-228 PSI on the high. Here's what I'm getting at 1500:
View attachment 3947953
That explains why it's not cooling. The pressure isn't high enough to cut off the compressor.
So where I'm at (could use guidance here).
a. Blockage somewhere (probably expansion valve)? Before I replaced everything I previously had to replace the hard line that runs along the drivers side fender/battery box. At that time I replaced the drier and expansion valve. Took apart the expansion valve to find it clogged with desiccant. I blew out all the lines but didn't find any other desiccant asides from that was at the expansion valve. Taking apart the cooler box again, I didn't see any desiccant this time either. Everything in the system is new now aside from the pressure switch/lines.
b. Excess air/contaminants in system? Not super sure on this, just basing off what the FSM says. Speaking of FSM...

Yeah, low side reading too low and high side reading too high can be an indicator of a restriction... what do the gauges read at idle? Personally, I find the FSM pressures to not be "exactly applicable" when measured in summer-time US continental south. To my knowledge, the FSM makes no mention at what ambient conditions those pressures are at, nor if the hood is open or closed at that RPM. I'd just take a reading at idle with the hood propped open and see what that shows.