A/C servicing; vacuum, oil and charge system? (1 Viewer)

[bucfl]

What sort of sound does a bad compressor make? I took mine to pep boys, they ran a vac, didn’t find a leak but told me the compressor may be going out. I asked the guy there and he just pointed at the engine. My untrained ears can’t tell if it’s going bad.

Also, I seem to be losing refrigerant. I tightened the valves and will check in a week.

 

[fooldall1]

When it engages, there is the usual audible CLICK noise as the magnetic clutch engages; then, for me the noise sounds not like a usual "mechanical whirring" but rather- a sound like bearings are failing, or beginning to fail. Since I replaced the Core, and the unit is 19 years old- I figured a refresh of the heart of the system can't hurt.

 

[bucfl]

I see. Mine engages, and i just hear mechanical whirring. I took a pick Monday of the guage and will compare the numbers next Monday to see if they are same. I’ve had two shops look at it and both tell me there is no leak yet the psi has dropped after a week.

Pressures have held after an hour of vac. Not sure what else it could be.

 

[fooldall1]

in the FSM- they give a range of scenarios that can help. Have you checked the troubleshooting guide in the FSM?

 

[bucfl]

in the FSM- they give a range of scenarios that can help. Have you checked the troubleshooting guide in the FSM?

I have not actually....let me see what i can find in there. Thanks for the reminder!

 

[fooldall1]

I have not actually....let me see what i can find in there. Thanks for the reminder!

It seems pretty comprehensive. Good luck man!

 

[fooldall1]

Post new compressor install.

 

[bucfl]

Nice! Do you actually hear yours clicking? I don’t hear mine click but it does engage and blow cold.

 

[fooldall1]

I need to test that part, that is say- listening to it engage. Initial impressions even inside the truck is basically that it's quieter by a LOT.

 

[fooldall1]

Experts: So, the Garage put in the factory amount of refrigerant, and it gets cold (as you can see). But, I recall seeing a fill chart somewhere that indicated filling the gas to a little HIGHER low side pressure for high-temp and high-humidity locations. For example, I think I saw the pressure on the low side at ~36-40. In the guide I saw, for this truck they went a little higher to 45-50 and got better performance- safely. Basically as @bucfl pointed out- you have to drive around a while to get pressure built up here (maybe its just the crazy humidity) to make it work at what I would consider cold. With a new compressor, and Evap core- I would assume that the performance should be better than I have for the first few minutes after start-up.

Am i just expecting too much?

 

[flintknapper]

Am i just expecting too much?

^^^^^ Yes, 'expecting too much'. It is normal for the system to take a bit to drop the vent temps. The reason for the common (but unreasonable) expectation that you should have cold vent temps immediately stems from a misunderstanding of how the A/C systems works.

Your system is one giant 'heat exchanger'. You Aren't pumping IN cold air, you are REMOVING heat from the cabin air. This takes time. You will need several complete air 'exchanges' before things begin to feel very cool.

Also, the higher your engine speed and the more air moving across the condenser (read highway speed) the better the system will work. It is not reasonable to expect the system to work as well at idle as it will at higher speeds.

There are two things going on every time you activate your A/C. First (and foremost) the system is removing the heat load (and humidity) from the cabin air (via the evaporator). ONLY after the system has had a chance to remove the bulk of the heat (keep your system on recirculate) does the effect of having air from the blower motor across the cold evaporator result in cold air being distributed from the vents in an effective way.

I know the two notions seem to contradict one another. Yes, when you first crank up your properly operating A/C unit...the air from the vents does feel cooler than the ambient, BUT at this point if there were no air exchanges...it would never get any cooler. With each air exchange you REMOVE heat. The absence of heat is what results in what we think of as cooler temps. As the heat load is slowly removed the system works better and better (to a point). Eventually...the vent temps 'can' approach the temperature of the evaporator and at that point...yes you are now blowing cooler air across the evap and out the vents.

Sorry to labor the point but it is well for folks to understand that an exchange of heat (moving it from inside the cab to outside the cab) is what is taking place. You are not (can not) just 'pour in the cool' with respect to refrigerant charge or vent temps.

There ARE (sometimes) gains to be had by 'optimizing' the refrigerant charge. IF you have the time and inclination, you can adjust the charge and see where it works best (it might be a bit under or over the factory recommended amount). But if you have 40°F. vent temps at highway speed (stabilized system) I wouldn't mess with it.

 

[fooldall1]

^^^^^ Yes, 'expecting too much'. It is normal for the system to take a bit to drop the vent temps. The reason for the common (but unreasonable) expectation that you should have cold vent temps immediately stems from a misunderstanding of how the A/C systems works.

Your system is one giant 'heat exchanger'. You Aren't pumping IN cold air, you are REMOVING heat from the cabin air. This takes time. You will need several complete air 'exchanges' before things begin to feel very cool.

Also, the higher your engine speed and the more air moving across the condenser (read highway speed) the better the system will work. It is not reasonable to expect the system to work as well at idle as it will at higher speeds.

There are two things going on every time you activate your A/C. First (and foremost) the system is removing the heat load (and humidity) from the cabin air (via the evaporator). ONLY after the system has had a chance to remove the bulk of the heat (keep your system on recirculate) does the effect of having air from the blower motor across the cold evaporator result in cold air being distributed from the vents in an effective way.

I know the two notions seem to contradict one another. Yes, when you first crank up your properly operating A/C unit...the air from the vents does feel cooler than the ambient, BUT at this point if there were no air exchanges...it would never get any cooler. With each air exchange you REMOVE heat. The absence of heat is what results in what we think of as cooler temps. As the heat load is slowly removed the system works better and better (to a point). Eventually...the vent temps 'can' approach the temperature of the evaporator and at that point...yes you are now blowing cooler air across the evap and out the vents.

Sorry to labor the point but it is well for folks to understand that an exchange of heat (moving it from inside the cab to outside the cab) is what is taking place. You are not (can not) just 'pour in the cool' with respect to refrigerant charge of vent temps.

There ARE sometimes gains to be had by 'optimizing' the refrigerant charge. IF you have the time and inclination, you can adjust the charge and see where it works best (sometimes a bit under or over the factory recommended amount). But if you have 40°F. vent temps at highway speed (stabilized system) I wouldn't mess with it.

Thanks for the reality check. I can only compare with my wife's lexus ls460 that blows cold pretty much immediately out of the vents even when it's been sitting closed up in the hot sun for a few hours. Cools QUICKLY. You're right, though. I think I'm just being a bit too persnickety about it.

 

[bucfl]

I think you and i are in the same thought process and im expecting too much. Mine never blew exceedingly cold from initial AC ON, but after a few minutes or more blows cold to the point i have to move the AC vents away. I think im looking for perfection and checking the pressures too much, seeing a fluctuation and thinking something is wrong. When i think its just the ever changing heat causing my self inflicted headache.

Reading the manual the other day it states 30-35 pressure in 86-95 degree. Mine is around 30+- and is blowing cold so far. I need to leave this sh*t alone! Im going to give my wife the gauge and tell her to hide it.

 

[flintknapper]

Thanks for the reality check. I can only compare with my wife's lexus ls460 that blows cold pretty much immediately out of the vents even when it's been sitting closed up in the hot sun for a few hours. Cools QUICKLY. You're right, though. I think I'm just being a bit too persnickety about it.

^^^^^

Yes, but not a fair comparison if you think about it. Now if your neighbor had a similar year 100 series that cooled pretty much right from the start (under the same conditions)...THAT would warrant looking into your system further.

But your wife's LS460 has MUCH less heat load to contend with and more modern components.

My LX470 has a decent A/C system but it would positively suck if I chose to compare it to my first vehicle in high school (1966 Mustang GT). On the hottest day in Texas summer heat...it would be blowing ice particles out of the vents in just minutes...no joke.

Similarly, if I were to compare the heater in my LX to the one in my 1970 model Bronco Half Cab...it would pale in comparison. Completely different cabin volume. The LX heats just fine...but it takes a few minutes. The Bronco has 3 heat settings that come on very quickly:

1. Low setting: Too hot...please turn it down.
2. Medium setting: It's too damn hot in here...turn it OFF!
3. High setting: Surface of the Sun hot. The high setting is NEVER to be used unless you need to warm up food.

 

[bucfl]

UPDATE:

I seem to have a new symptom. After two weeks of no issues, yesterday it blew cold then just cool the rest of the day and been like as of this post. I stopped by to check pressures at autozone and i have 30-35 L and 50 or less H side. I came home and lightly tapped the compressor with a hammer. Turned car on and heard it engage, off then on and engaged again. But still no cold AC blowing.

This is after replacing evap, exp valve, and dryer. I checked sight glass and see good flow of refrigerant and dont notice bubbles.

Does this look right?


Looking at FSM AC page AC-8 (9) Defective Compressor Compression:

 

[fooldall1]

Yup, looks right... I replaced the compressor and i'm glad I did- there is a clear grinding of bearings when turned by hand, it would not have been long until the compressor failed and then- you know the rest of that story.

I got the Denso OEM Compressor from Amazon and replaced it after the busted Evap Core in the front:

https://www.amazon.com/gp/product/B001UCBMJK/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1


Works like a champ. Now I have to focus on the Rear evap core, it's bound to be dirty as F.

 

[bucfl]

Added to amazon cart.

 

[fooldall1]

Added to amazon cart.

Do it Do it Do it

 

[flintknapper]

UPDATE:

I seem to have a new symptom. After two weeks of no issues, yesterday it blew cold then just cool the rest of the day and been like as of this post. I stopped by to check pressures at autozone and i have 30-35 L and 50 or less H side. I came home and lightly tapped the compressor with a hammer. Turned car on and heard it engage, off then on and engaged again. But still no cold AC blowing.

This is after replacing evap, exp valve, and dryer. I checked sight glass and see good flow of refrigerant and dont notice bubbles.

Does this look right?


Looking at FSM AC page AC-8 (9) Defective Compressor Compression:

If you aren't getting cold air from the vents, you know the manifold gauge is accurate and high side pressure won't build...then yes, replace compressor. You can block the condenser with a piece of cardboard (impedes air flow) and watch to see if the pressure rises significantly, if not...the compressor is knackered.

 

[bucfl]

I just wanted to close the loop on my issue. I followed the FSM and thought the issue was the compressor. I ordered one but prior to replacing it i did another search for leaks. I found the corner of the condenser wet. So i returned the compressor and replaced the condenser. No more leaky refrigerant.

Two issues i had. The Evap and condenser were both leaking. I know it was the Eavap because when i used Red Angel Stop Leak i saw pink liquid coming from the drip line of Evap. What a pain... but glad its all sorted now.