Hello Everyone,

I am having issues with the A/C in my 95 SR.
For a while now my AC will work for a short while after I turned it on and then it wouldn't be cold anymore. Now when I turn it on I get no cold air. Went to autozone and the guy there told me to just add some refrigerant. I don't know much about AC but I thought you have to check the high and low pressure first. Is the autozone guy right? Can I just go ahead and add a can of refrigerant and see what happens or are there other steps I need to take first so I don't make my situation worse?
Hopefully its something simple to fix and not an electrical problem or something.
On a little side note, presuming if I have a leak, has anyone used the refrigerant with the sealant and did it work?

Hopefuly one of your knowledgeable minds can help me out.
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Thanks,
Mike

On my 96SR it sometimes have the same problem. For me it's a problem with the AC cooling fan not staying on. <img src="/forums/images/graemlins/frown.gif" alt="" />

If you add refrigerent you'll need to at least know low side pressure so you don't overfill. It's best to have a set of hi/lo gauges before you add refrigerent because the problem may be the compresssor clutch or condensor fan and not low refrigerent. First I'd lift the hood and see if the clutch is engaging and the fan is operating as there may be enough pressure to activate them but not enough to give cold air. Also check the compressor belt tension. I think some of the refill cans have an attached pressure gauge which I'd recommend, but the correct pressure is related to ambient temperature. There should be a chart on the package of the refill kit, but you're probably looking for about 35psi at about 90F. Put the system on recirculation with the doors open so that hot engine air is not sucked into the vent system and engine RPM at about 2000, slowly fill a bit at a time to let the system even out. Don't hold the engine at 2k for too long as you could overheat the CAT and may trigger the check engine light. 134a, which is your refirgerent, leaks faster than the old R12 and some of the new replacements, so gettting the leak fixed is advisable.

The sealant is usually to soften and swell the soft seals like o-rings, but it will not work on the compressor seal, which on a 95 is more than likely where your leak is. If you see a build up of black greasy dirt behind the compressor clutch then that would indicate a leak at the shaft seal. If you continue to refill a leaking system then you'll need to add oil to the system, but that becomes a guessing game as to how much. One small can of refrigerent with oil can't hurt, too much oil will reduce cooling and could harm the compressor. There is also a dye in some refill kits that will help with finding the leak. If it's the shaft seal then that should be able to be replaced without buying a new compressor. Here's a good place to get A/C parts, tools, etc. http://www.acsource.com/index.asp

All systems will lose charge over time. As mentioned the 134 leaks faster than R12 in the same system. To get around this, 134 systems used barrier hoses that reduce the leakage rate through the hoses.


Oil will leak a lot slower unless you have a real leak (broken line bad seal).

A good test would be to check to see if the low-pressure switch is open or not. If its open opens when the AC is on then adding a can of refrigerant is a low risk test.

My understanding is if the low-pressure switch opens both the clutch and the AC fan will be off, they are on the same circuit.

I would get a meter out and test the low-pressure switch.

Kevin

if the the compressor clutch is not kicking off and on and the air from the dash starts out cold then turns warm and the clutch is not kicking off and on then it is your expansion valve they are about $45.00

I added refrigerant and checked the pressure on the low side and it is within range but I am still having the same problem where it will either be cold and then warm or start warm and stay warm.
Does that mean the expansion valve is not working correctly or is it another issue.

Have you checked the operation of your AC fan? It seems that AC won't work if the fan doesn't turn. That least thats the behavior i've seen on my 96SR which is pretty much the same as your 95SR.

The AC fan is the one in the front of your radiator. Simply start your engine, Turn on the AC, then check if that fan is turning.

If it's not, try to get it to spin then check if the AC begins to work.

In mine, the Fan was dead. Once I replaced it with a fan (used one from the junk yard), my AC began to work again.

Only problem for me is the fan sometimes stops spinning especially when the engine gets hot so it stops spinning and when that happens, the AC shuts off.

The TXV acts independent of the compressor cycling and reacts on incoming ambient air temperature. High ambient will mean more refrigerent flow, less ambient less flow. If the TXV is sticking, then to produce warm air it would have to not allow enough refrigerate flow to meet ambient air temp demand. The compressor cycling is determined by the two temperature sensors on the evaporator, one on the inlet air and one on the outlet air to keep the evaporator from freezing up. If the TXV is not allowing enough flow then the evaporator will not be cold enough and the temperature sensors on the evaporator will not tell the compressor clutch to disengage. Since it seems there is enough refrigerant then I would look at the compressor clutch when you are getting warm air. If it is engaged then it's probably the TXV, if it's not engaged then it could be one of the temperture sensors, or even the A/C control unit.