2nd Gen Non-Engine/Transmission A/C acting up

[MParrott]

Man its hot in my truck!!!!! My compressor is working but only for about 2-3 seconds at a time. I bought one of those gauge/R-134 bottle combo's from the parts store and hooked it up to my truck. when the compressor runs it drags the system pressure down to zero, but when it cycles off the pressure goes back up to normal according to the gauge. Am I supposed to read the gauge when the compressor is running or when the compressor is idle. If I need to read the gauge whe the compressor is running then i need some freon, if not I may have other issues. I jumped the switch on the accumulator and let the compressor run for less than 10 seconds and got very little cold air. Also all the fuses and relays that connect to the A/C system are good. I have searched the forums for others having similar problems as mine but I could not find one with my exact problem. This Atlanta heat is killing me without my A/C. thanks

 

[pbell]

Mine did the same thing! I took it to the A/C repair shop and they said "the pressures are fine" and another one said the "pressures are low. " The shop that told me they were low looked everywhere underneathe the hood and found the leak. He said it was the evaporator core and now I am in the process of replacing it. Do a search on "evaporator" and you will see. I would take it somewhere to get it looked at just dont add freon. You could damage more than what already damaged. $$$$

 

[tmilam]

Having the same problem with my 02. Had the compressor replaced last summer with no changes. I put a thermometer in the center vent, 60 deg on regular air at hiway speeds, 68 in town. 40-44 deg on max air. When the shop checks it, they say everything is working fine. What gives.

 

[TXDSLSHOP]

When the system is low on freon the compressor will cycle. The compressor runs until the low pressure switch tells it to shut off and the the system equalizes and the compressor comes back on because the low pressure switch now has sufficient pressure. Add freon until the low side is around 30 as long as the high side does not go over 200 or so. The compressor will be running constantly. If it has plenty of freon and it is not cooling then check your radiator, intercooler, condenser for blockage. Pull the radiator and and clean it and clean the others in place. You must have good air flow over the condenser in order for the system to work correctly. Hope this helps.

 

[MParrott]

thanks for the help. I checked all my connections again and also for air blockage around my A/C components. I think that the system is just low on freon. because the compressor kicks off when the gauge level says my pressure is near zero. And also it only takes about two seconds for the system to show no pressure. I will try to charge my system and I'll let ya'll kniw how things turn out. Thanks again for the help. This has got to be the most helpful site on the internet!!!!!!!!!

 

[TXDSLSHOP]

Good luck, I would add freon until the low side is around 30. This should take of it, if not give me a shout. Remember, the freon is going somewhere, you might add dye to the system to help find the leak. Jeremy.

 

[B.G. Smith]

thanks for the help. I checked all my connections again and also for air blockage around my A/C components. I think that the system is just low on freon. because the compressor kicks off when the gauge level says my pressure is near zero. And also it only takes about two seconds for the system to show no pressure. I will try to charge my system and I'll let ya'll kniw how things turn out. Thanks again for the help. This has got to be the most helpful site on the internet!!!!!!!!!

Don't add more than two cans,(R-134A) the system only holds 32 oz. Watch what you buy, some of the stuff they are selling has two ounces of oil in the can, if this is the first time the unit has gone empty you should not need to add oil. bg

 

[MParrott]

After putting in a whole can of freon... ..... I have very cold air again. Thanks for the help guys i could not have done it without your input

 

[Andy Redmond]

I recommend finding the leak.



Check the low psi switch on the accum/dryer, the oring will dry out a bit and allow for a pretty good leak sometimes.



Have the shop run the a/c, then remove the blower resister on the blower box (near blower motor, passenger side) and stick the "sniffer" up in the cavity (with truck shut down). If the evap core is leaking the sniffer will go "wild. "



Its a 5-8 hrs. job (most flat rate manuals) (Evap core labor/ R&R). Change the heater core if you go in, as its sure to go next. Then evacuate and recharge. Many shops will put in 36 oz. If you put in only 30-32 oz. the center vent temp will be colder.



I've played with some "adjustable vs. fixed" orfice tubes recently with some good sucess.



Good luck

Andy

 

[MParrott]

Got bad news again,



My A/C has stopped working all together. When I select A/C on the dial, all I get is what feels like vented outside air. The compressor never engages and the engine rpm never change. I hooked my pressure gauge up to the system and the pressure is still good. I checked the relay and it was good. Also I jump the low pressure switch on the condensor and the compressor ran for the 3 seconds that i had the jumper on it. what else could it be? I am not very good with these A/C components but I want to try and fix it myself to save some $$$

 

[Andy Redmond]

Sounds like the system may have lost its charge.



You state the pressures are good. . you didn't tell us what they are though, so I won't speculate.



Good pressures will not be noted unless the compressor is engaged and running. What were you pressures when the jumper was on the low psi switch? Are they comparable with the FSM. . ?



Provided the charge (freon) is ok. . look at the electrical system that engages the compressor clutch. .



Have you verified good voltage at the compressor clutch, good ground etc.



What is the resistance measurements in ohms on the compressor clutch coil when testing it while unplugged from the wiring harness? Does it match up with the specs. in the FSM. .



I'm going to step on my soap box so please listen to a opinion and hear some good advice. You are ultimately adding exponentially to your repair bill by bandaging something that needs a suture.



After the system is found to be low you are adding HFC134A charge and may or may not charging it to the correct level (under or overcharging, do you have a scale?). Hopefully you haven't added anything that acts as a leak sealer. . it can contaminate professional equipment, which will cost more should the system be diagnosed by a professional shop.



You likely are getting air into the lines when recharging. Ambient air is moist and doesn't compress well with refrigerants, which can cause acidic affects inside the compressor and components. When the system is empty it should be evacuated (pulling a vacuum with a vacuum pump) for at least 30-40min. sometimes more in hot and humid weather ( I usually go for an hour).

When a vacuum of 29 hg is achieved moisture will begin to boil and disapate (sp).



I've previously outlined the common leak points, you may need dye and a good black light or a electronic sniffer to find your leak. It might also be necessary to remove the compressor clutch to see if the leak is around the compressor shaft seal.



The tools to do this well are expensive and not usually re-used often by the home mechanic, making them unfeasible to purchase for a one time repair.



Vacuum pump $300-600.

Manifold guages (economy) $75-100.

Electronic sniffer $150-$2000.

UV Light and Dye Kit $69-350.

Compressor clutch tools (Miller Special tools) $200. //aftermarket $100.

Without a recovery or recycling equipement usually refridgerant must be vented a bit to attempt to purge the air the manifold guage line when recharging. (venting is illegal for licensed mobile a/c techs). Recovery and recycling machines. . $600-6000.



Now you have a bit of knowledge why a/c repair costs so much. Are their lots of scam artists that perform a/c repairs? Absolutely, ask around and you'll likely get steered towards and ethical independants or reputable dealers.



If your maladies are electrical, I would ask around and find some good electronic techs in the auto electric business. A good start might be to a technical institute and find out from the instructors who in your area snatches up the "super-star" pupils.



Good luck and let us know what you find out.



Andy

 

[BHanna]

I agree with Andy here. You've got a leak and it needs to be fixed before you can really proceed. After it's fixed, the system needs to be vacuumed and then recharged with the right amount of R-134a. The cans with the gauges on them are band-aids. They only make the A/C cold long enough for a used car salesman to move the car off the lot. (No offense to any good used car salesmen out there)

 

[MParrott]

Thanks for the replies. I think I will take it to a prfessional repair shop and let them look at it. I wanted to do the work myself, but I think this may be to time consuming. I will keep you guys posted on the findings and repair of my A/C system

 

[B.G. Smith]

Got bad news again,



My A/C has stopped working all together. When I select A/C on the dial, all I get is what feels like vented outside air. The compressor never engages and the engine rpm never change. I hooked my pressure gauge up to the system and the pressure is still good. I checked the relay and it was good. Also I jump the low pressure switch on the condensor and the compressor ran for the 3 seconds that i had the jumper on it. what else could it be? I am not very good with these A/C components but I want to try and fix it myself to save some $$$

The low pressure switch is located in the side of the accumulator, is that the one you by-passed? If the pressure in the system is above 45# the switch should be closed and the compressor should run when turned on, if it is below 25# then the switch will be open and compressor won't run. Could be just the switch. If the switch is in fact in the condenser as you state then it is a high pressure switch and could also be bad but i'm not sure if the system has a high pressure cut out switch????(Just checked my manual, it does have HP cut out switch and it is located in the discharge line right after the compressor. ) If it is the low pressure switch, it can be changed without discharging the system, it is screwed into a schrader type valve. bg