2nd Gen Non-Engine/Transmission A/C questions

[DSiemens]

I added some R134a to my system. I started out with a system that was engaging and disenganing the compressor. I suspect that I have a slow leak, ie over years to go down. Last year A/C was getting pretty lousy. This year it was finished.



I added R134a until I got pressure on the low side to about 24lb. I do not have a high side pressure guage. What risks & problems do I have? The outside temperture was about 88 tonight when I did this. I know the air is a lot cooler, not ice cold, but pretty good.



Should I add R134 until I get to 30lbs?

 

[ironbutt]

Auto Zone sells a R134a canister with a stop leak additive in it, It is about $12 bucks for the can. Trouble is the darn engine is so noisey, that you can't hear the flow from the can. "Ironbutt"

 

[BILLVO]

If you do not want to cause yourself even more problems. PLEASE PLEASE DO NOT EVER PUT ANY PRODUCT IN YOUR AC SYSTEM CONTAINING A STOP LEAK ADDITIVE!!!!!!!!!



It can and will plug your orfice tube or expansion valve and also clog your fine tubes in the evaporator and condensor and possibly ruin your compressor any way you look at it it will lessen the effeciency of the system. It is not that expensive to find and fix the leak cheaper than the consiquences of stop leak.

 

[BILLVO]

I added some R134a to my system.



Should I add R134 until I get to 30lbs?

You should really get a set of gauges to monitor high side it is more important than low side. I will say that at 30 psi on low side you have already overcharged it which will cause the receiver drier or accumulator to freeze up causing it to lose cooling ability. at 80-90 degrees you should be at 150-170 lbs at high side and about 10-20 at low side when it cycles out. high will drop and low side will climb this varies with ambient temp and system pressures.



Hope this helps.

 

[Bob4x4]

You should really get a set of gauges to monitor high side it is more important than low side. I will say that at 30 psi on low side you have already overcharged it which will cause the receiver drier or accumulator to freeze up causing it to lose cooling ability. at 80-90 degrees you should be at 150-170 lbs at high side and about 10-20 at low side when it cycles out. high will drop and low side will climb this varies with ambient temp and system pressures.



Hope this helps.

I don't know where your specs come from... ... ... . not very close to factory specs.



@ 80 degress ambient 1ooo rpm windows closed about 55-60 degrees @ the ctr outlet. low side should be 40-50 psi and hi side should be 175-215 psi this will vary with humidity of course. Of course what does D/C know???? :-laf



Bob

 

[B.G. Smith]

I added some R134a to my system. I started out with a system that was engaging and disenganing the compressor. I suspect that I have a slow leak, ie over years to go down. Last year A/C was getting pretty lousy. This year it was finished.



I added R134a until I got pressure on the low side to about 24lb. I do not have a high side pressure guage. What risks & problems do I have? The outside temperture was about 88 tonight when I did this. I know the air is a lot cooler, not ice cold, but pretty good.



Should I add R134 until I get to 30lbs?

The system holds about 28oz. of 134-A. Your pressure is just above the cut out pressure of the clutch cycling switch. (Should cut off at 25# and come back on at 43#. ) Sounds like you are still a little short on refrigerant. If the compressor is still running when the suction pressure goes to 10-20# then the cycling switch is bad. Bob 4X4 is right on and I agree with Bilvo on not putting anything in your A/C system but oil and refrigerant. bg

 

[DSiemens]

Does anyone know what the specs from the manual?



I will purchase a set of guages to read the high output.



Thanks to all for the help.

 

[B.G. Smith]

Sorry, I didn't mean to offend, if we are going to help in this case we need to get closer to the specs. You can't get to 10-20 on the low side if the system is operating correctly, the clutch cycling switch opens at 25 pounds. From the 99 factory manual: "Engine warmed up and rpm set at 1000, outside temp. at 90deg. F, center panel outlet air discharge temp. , 55 to 60 deg. , suction pressure, 50 to 60 lbs. , discharge pressure, 215 to 270 lbs. Note, if pressures are lower than shown, but center panel outlet temp. are OK, then the A/C system is OK. " bg

 

[Bob Cochran]

I was wondering since you all seem so knowledgable. I have gauges I purchased years ago but for the older R12 systems. Can you buy adapters to convert it to R134? Thanks for the help.

 

[BILLVO]

I was wondering since you all seem so knowledgable. I have gauges I purchased years ago but for the older R12 systems. Can you buy adapters to convert it to R134? Thanks for the help.

You can get adapters. I have a set from snap-on. But it would be cheaper to get a new or used set of gauges or replacement hoses. I would shop around to see what would be best for you.

 

[Grizly]

Hey , I can't find any thing on my problem but if I may jump in here maybe you guys can help me: My a/c system works good on high but when shifting thru gears while driving some times kicks off compressor? when I get on throttle and boost up to say 27 for a bit then it kicks back on compressor? don't know what to do...

 

[DSiemens]

So the low side is up to 40lbs than and the outlet should be less than 270?



Is that correct for 90f?

 

[B.G. Smith]

So the low side is up to 40lbs than and the outlet should be less than 270?



Is that correct for 90f?

Yes, between 215 and 270 deg. F, that is the figures given for a controlled situation at 90 deg. F outside air and engine at 1000 RPM. Note that they say if pressures are lower but center panel temps. are ok then the A/C is ok? bg

 

[B.G. Smith]

I was wondering since you all seem so knowledgable. I have gauges I purchased years ago but for the older R12 systems. Can you buy adapters to convert it to R134? Thanks for the help.

http://da.harborfreight.com/cpisearch/web/search.do?keyword=manifold+gages&Submit=Go

 

[B.G. Smith]

Hey , I can't find any thing on my problem but if I may jump in here maybe you guys can help me: My a/c system works good on high but when shifting thru gears while driving some times kicks off compressor? when I get on throttle and boost up to say 27 for a bit then it kicks back on compressor? don't know what to do...

The A/C compressor clutch engagement is an output of the PCM, I believe it delays the engagement a few seconds when the engine is started and the A/C switch is in the "on" position. On some autos the A/C cuts out under hard acceleration to allow the engine to have more power for passing/climbing etc. but I don't think that is the case with our trucks. That may be a fun problem to solve????? bg

 

[Grizly]

thanks for input, I have had others look at this but all have stated to find a a/c specialist to fix . . none found yet. .

 

[Bob Cochran]

Billvo & B. G. Smith thanks for the advice it is probably the way to go. Thanks

Again.

 

[DSiemens]

Does everyone agree that the following is true,



High side should be less than 270lbs

Air temp outside at 90F

Low side pressure should be between 25 and 43, but really not important as high side less than 270.

Engine speed should be 1000rpm.

Vent temp should be 55-60.



Lower than 20lb the compressor will not activate or turn of and on as low side pressure fluctuates between over 20 and below.



What else am I missing?

 

[BILLVO]

.



What else am I missing?

Don't forget your original problem,a leak. Have a shop put a dye solution in the system or buy a kit and do it yourself. The leak will show up after a couple weeks of ac use. A black light or infrared light depending on dye solution is used to find where the leak is. Different dyes will show up as a highlighted color under lights color depends on the dye,green or yellow are the most common. I am trying to save you future headaches by fixing the simple problem rather than adding $$$$freon all the time. as far as pressures as everyone has given reference to. nobody has said anything about if the system was totaly dead then there will be air in the system and without pulling a vaccuum on it to get a clean freon charge (no air or moisture) you will never get to the optimal cooling temp and pressures will be off also.

 

[DSiemens]

I was thinking that the system was entitled to leak a bit. It's about 150K now.



What do you use for a vacum pump for this?