Dash A/C not blowing cold

[Janss]

My dash a/c has been recharged with refrigerant 3 times in the last couple years by 3 different mechanic shops. They've all tried to find a leak to no avail, using dye and blacklight. They say maybe there's a leak deep inside the system that would cost hundreds of dollars to take apart, and might be less costly just to get the system recharged every 6 months or so.

Seems to work for awhile after being recharged. But after sitting on the Oregon coast for a couple months last summer, the a/c stopped blowing cold. Had it recharged again when I got home. Worked for awhile. Now after sitting in central AZ a few months, not blowing cold again.

I know nothing about this stuff. Anyone have any thoughts? I just want to sound a bit knowledgable, or maybe have suggestions, when I go back to see one of those mechanics (or a new one). Or maybe what they've told me is all there is.

Chevy 8.1L with Allison transmission.

[Janss]

Very good info, thanks again. Gives me alot of information to discuss with a mechanic.

Might wait until I get home and take it back to one of the shops near there. Meanwhile, I'll try running the generator and turn on the house a/c while driving. Never done that before, but have read others do.

[Gjac]

On my older Chevy I found the problem to be a leaking trinary switch, some have binary switches, but this switch is about an inch in dia and an 1.5 ins long with three male connectors on top. I did not see it until I added dye to the system and used a UV light that came with a fill kit. The kit was less than $30 at Advanced Auto. What I thought was just motor oil on top of the switch was the coolant leak. Replaced switch and filled with the R-34 can and all was well again. You can just check the top of the switch to see if there is an oily substance on top. I assume the other shops checked all the other common places for leaks.

[drsteve]

Janss wrote:
So why not environmentally friendly? Is it different than a shop putting it in?

It's not who puts it in, it's allowing it to leak out over and over that is bad for the environment.

[allbrandauto]

as a auto shop owner Freon leaks are the hardest thing I have to do you need to find somebody that really wants to fix it when I see one that take a couple of months to leak out its usually a evaporator leaking 2 ways to find it are with a really good sniffer take the blower motor reisister out and sniff it there next way is with dye collect the water coming out of the evaporator drain and use the light to see if you see and green

[Janss]

So why not environmentally friendly? Is it different than a shop putting it in?

I'd have to have a mechanic show me how to do it anyway. But I thought the a/c system is under high pressure and not advised for a lay person like me to add refrigerant. (Like lots of other things, I'm guessing it's based on each person's comfort level.)

[sch911]

steveh27 wrote:
I spent several hundred dollars to repair shops trying to find & fix the leak on my 1997 Xplorer on a Dodge 3500 van chassis. Then I bought the hose fill kit and put in 2 cans in the spring and it works all summer. Need to redo each spring, but the cans are only $5 each so it's good for me.

Not the environmentally friendly answer but this is also what I do. Learn how to add a couple cans of refrigerant and go on your way...

[dougrainer]

harold1946 wrote:
Go to irv2.com and check in the Workhorse forum. This is one of the known issues with the tem-con valve of that era.

Tempcon valve is the HOT water side, not the 134a side. Doug

[steveh27]

I spent several hundred dollars to repair shops trying to find & fix the leak on my 1997 Xplorer on a Dodge 3500 van chassis. Then I bought the hose fill kit and put in 2 cans in the spring and it works all summer. Need to redo each spring, but the cans are only $5 each so it's good for me.

[Janss]

Great comments. Thanks for all the input.

[sneakygroundbuz]

i would check your evaporator core for a leak,and i would also check the thermal expansion valve(if it has one),also check the receiver dryer for a leak(they like to rust up where the straps go around them.compressor seals will leak due to age,as will the other seals in the system.

i was an auto tech for 25 years,a/c work was one of my specialty areas.these are common areas for leaks that are hard to find because they are usually hard to access.

best way to find them is with a high quality freon detector(sniffer)

any time you have a leak,freon goes out so does your refrigerant oil and air goes in.
so just refilling it isnt a great idea. air contains moisture,moisture in your a/c system will eventually cause your compressor to fail due to loss of lubricant.

good luck

[wa8yxm]

I have that problem with my car. On my Motor home I don't know yet.. I re-charged it last summer after replacing the compressor.. And some other stuff. But that is one spot where a leak is hard to find.

[KD4UPL]

I had a similar situation with a '96 Dodge pick-up. A shop would recharge but declare they couldn't find the leak. In six months it would be done again. Recharged it, can't find the leak. I just ended up going to Auto Zone or Advance or where ever and getting the can of freon with the little gauge and hose and recharged it myself. I carried a can of freon around with me. When the AC would start to get warm I'd put some more in. The can was only about $20 so it was definitely cheaper than paying shop labor to find the leak.
Eventually someone told me that with systems of that vintage this was a common problem. Supposedly this was around the switch from R-12 to R134a or something like that. It seems the new refrigerant has smaller molecules that tend to leak around the seals worse than the old stuff. This made the leaks even harder to find. I don't know if that was true or not.
I will say that my '05 Chevy truck, which must be nearly the same as yours, has never had the AC serviced in it's lifetime and it still blows very cold air. So, I do think you have an actual leak somewhere.

[harold1946]

Go to irv2.com and check in the Workhorse forum. This is one of the known issues with the tem-con valve of that era.

[midnightsadie]

I,d just act like nothing ever happened before ,a good shop has the tools and the knowledge to find the problem. if you tell them four other shops have played with it,they might not want to spend any time on it,