A/C advice

[capecove]

Hello there folks!

 

I need your advice once again, if you wouldn't mind. I have the most bizarre situation with our R-134 based A/C in the 1992 Loyale. It works great for the first few minutes you turn it on and slowly goes downhill into just vent air shortly after that. Turn off the A/C switch (push bi-level for instance), drive for a few minutes, press A/C again and presto, you get cold air again. Then the whole cycle starts again. Somebody had converted it to R-134 according to the sticker. I checked the pressure of the system and it is around 30 PSI, which seems good enough by me (and my gauge).

 

Any advice out there for us?

 

Thanks!

 

Jason

[nipper]

Ac is way more complicated then that. Please if you do not know what you are doing, take it to a shop. Its one of the few places under the hood where you can seriously hurt yourself (and not in a "here hold my beer" way).

 

You need to take a low pressure and a high pressure reading with the PROPER gauges.

 

It sounds like your low on refrigerant. You can build up pressure till the volume of gas you have goes through the expansion valve, then there is no more coolant to supply the compressor. You most likely have a leaking O ring too.

 

nipper

[erik litchy]

my car has the original charge, what happens is the belt slips and the computer turns it off so it doesnt wear out the belt.

so either tighten the belts or change them.

[rllywgn]

i agree with nipper..

 

but you can check a couple things.. Is your electric fan coming on? theres a combination high pressure/low pressure switch. it will shut down the compressor if either is met until they reach a set cut in/out point.

 

you could be undercharged, and its cutting out on low pressure. or on the flip side if theres not adequate cooling going through the condenser it could be going off on high pressure.

 

 

r134 is not meant to be in a r12 system. the condenser coil is to small and most of the time ive seen the conversion done it's been overcharged. it takes longer for a system to "cut in" after a high pressure hit.

 

if it was converted by a "shade tree" mechanic it probably wasnt done properly, and in alot of cases licensed shops dont even do it right.. they don't have to, the law doesnt require it anyways..

 

 

I am a certified (609 and 607) hvac technician. working in the commercial service field in las vegas..

[capecove]

Well, thanks guys. I guess off to the shop she will go eventually. There is a sticker under the hood reading R-134 (right next to the original R-12 sticker), it is an aftermarket sticker. Also, there are two what look like adapters screwed on the high and low pressure ports. I was able to use my gauge set for my F-150, they fit fine and the low side pressure read 30 PSI, like I said before. I am unsure about when the conversion was done exactly.

 

Oh well, so we just go spend some money to have cold/warm dry air... LOL...

 

Thanks for your assistance all!

[idosubaru]

working with A/C isn't all that hard. there's TONS of information on the internet about working on A/C systems. read up and do it yourself.

 

more than likely you just need some more refrigerant. save yourself some cash and buy one of those cans with the integrated gauges for $20 from the autoparts stores and follow the directions. sounds like you're low on refrigerant.

 

if you're lucky the guy before you just used one can, which isn't enough for an empty system. if yo'ure not lucky you have a leak. but even those can be easy to fix.

 

a common item needing replacement are the orings and schrader valves. they cost about 50 cents each but you'll end up paying $400 to have a shop work on it.

 

you have the option of just replacing the couple orings that are easy to get to now (the ones on the compressor are more likely to leak) and the two schrader valves as well. replace those then recharge.

 

if you're getting some cold air now there's a really good chance that your system is working fine and you don't have any substantial leaks except those minor parts i just mentioned. a major leak or faulty component and you'd have no cold air.

[derburger]

I'm wondering about my 86 XT's AC system as well. Unfortunately it was converted to r134a in 2004 and I assume most of it has leaked out by now. I'll probably recharge it and see if the A/C is acceptable with r134a, which is unlikely.

 

My MB 300cd it was converted to r134a before I bought it and the compressor ate itself. I flushed out the system, replaced compressor, drier and expansion valve, vacuumed out refilled with r12 freon, now the 29 year old car cools like a modern one or better. A/C work isn't that hard, usually I don't bother with having r134a converted systems since they don't cut it.

[idosubaru]

i would'nt write off the R134a that quick on one or a couple experiences. i've done a bunch of conversions and hit them with actual temp gauges afterwards and they do a great job.

 

yes there are "technical" reductions with R134a but you'll find the functional losses negligible.

 

i think older cars tend to have other things compounding a/c inadequacies. get everything working well and charged properly and they do great. for instance you didn't mention flushing and replacing all sorts of parts before charging with R134a - had you did that there's a good chance you would now be a believer.

 

i don't even really pull a proper vacuum all the time (shhhh!!!) and they still do great.

[nipper]

i don't even really pull a proper vacuum all the time (shhhh!!!) and they still do great.

 

I'm tellin !