Question about A/C for you pros and smart people :-).

Hello,

I have a 96 suburban K2500 454.

I bought this Suburban last year and the air has not worked since. Now that the Cleveland weather is 90+ and very humid I decide to take a look at it. I have had great luck in the past from your advice and find the knowlegde base at these forums priceless.

here's the deal -
I found what I believe is a pressure switch attached to the dryer - the wired plug was unattached. As soon as I attached it the compressor kicked in and appeared to be operating normally. I filled up the freon to 40 psi.

My dilema is that the air inside is not blowing cold. The return tube from the condensor is ice cold. The low side line off of the compressor isn't hot but it is definately not cold (not sure if it should be).

I haven't check out the evaporator coil yet - I am imagine it will require me to pull out a good part of the dash to do so.

My questions are this: Is there something that could be blocking the freon from getting into the evaporator coil? Could a dryer go bad or get clogged? If there is a pinhole leak in the evaporator coil - would that prevent it from getting cool? (but would I loose all pressure in the system over time? - which I haven't)

I suppose if I expose the evaporator coil and it's not cold that would tell me somethings up.

Would you recommend me filling up the freon to the full 45psi?

Any advice is greatly appreciated.

Cheers!

Signed Confused in Cleveland. :banghead:

- Jim

If the doors (or Flaps) are not opening then you will not get cold air coming out the right places. If you are getting a good quantity of air at the proper vents then the flap motors are ok. You said that there was air at proper vents, and your dryer where the switch was unhooked is getting cold, so the compressor is doing its job. I have seen mice get into the heater/ac and build a nest inside blocking the coils inside. Check this by taking out the blower motor and looking inside

I have seen mice get into the heater/ac and build a nest inside blocking the coils inside. Check this by taking out the blower motor and looking inside


Thanks for the reply and the tip, I'm grasping at anything to figure this one out. It's worth a shot, I will check it out tonite. I seem to be getting air out of the right places but if somethings blocking it from passing over the coils....that would do it. Arrrrrgh!

Thanks again...

Hi,I've seen this happen before (similar anyways)return tube frosts over w/ no cold air.Could be blockage,I have had success by recovering refrigerant vacuuming.Good Luck!

I'm no A/C expert but what about the orifice tube? Which if I'm not mistaken is like a little filter. If that is clogged that could be causing your blockage. I know they are cheap too.

Wow, I have a few good ideas to try. I am going to check out the coils for blockage, followed by the recover/refill then I'll check out the orifice tube. I'll do some investigating to find out where the orifice tube is on my truck.
I'll have to try this Saturday morning. My wife may think I'm up to something if I'm out too late at night poking around for an orifice tube!
:-p

Thanks for the help/tips guys, I'll keep you posted!

If your return tube is ice cold that means that the orifice tube is working. Did you convert to r134 or is this a r12 still? Orifice tube is at connection directly in front of high pressure gauge fitting on fenderwell on pass side.

If your return tube is ice cold that means that the orifice tube is working. Did you convert to r134 or is this a r12 still? Orifice tube is at connection directly in front of high pressure gauge fitting on fenderwell on pass side.

This has always been an R134 system. If it was converted it was before I owned it. But I believe it was R134 from the getgo - the dryer is marked as such.

Yeah you're right 94 and up are 134a systems.

Yeah you're right 94 and up are 134a systems.

R12 was much better, but with all good products it was harmful to the upper atmoshere, who cares does anyone hang out in the upper atmoshpere? I don't, and i'm not planning any trips there in the future.

R12 was much better, but with all good products it was harmful to the upper atmoshere, who cares does anyone hang out in the upper atmoshpere? I don't, and i'm not planning any trips there in the future.

I beg to differ, Its close to the same. I have a 1990, when I had full R-12 in ir, it would blow 40 degrees.

Now that I converted it to 134 (new compressor, and dryer) I get 38 degrees. No complaints here...just make sure u do it right.

To start with if you kept pumping in refrigerant until you reached 40psi on the low side you are slightly over charged. adding more will only reduce the cooling capicity further.
The lower you can get the low side pressure without the compressor cycling off the colder the air will be.
I run my R12 system at 28 psi on the low side and I get 34 degree duct temperature. I get frost all the way to the back of the compressor.

Thanks for all the replies. I have yet to start working on the suburban again. Still hot here in Cleveland.

My wife and I went out to look at new cars before the "employee discount" ended. We looked at everything - Cadillac srx & GMC envoy to Ford Windstar, explorer, honda oddessy, pilot (by the way the Honda ridgeline was something I hated until I got in one - impressive), Dodge caravan, Chevy (Me a Chevy owner) - I found the chevy uplander and trailblazer to be lacking for the price. The Buick line felt and looked better but I was shocked at Chevy (I guess I expected more). How could they put out an SSR and leave the trailblazer and uplander looking and feeling like that? My wife ended up with an '05 Pacifica touring (sticker 31K - bought 24K). The price was in our low price range (even though I fell in love with the Chrysler 300..WOW).

So to make a long story longer, I am driving my wifes Honda Accord with working AC before we turn it back in on the lease. I will have to get the AC working in the Burban this weekend so I will keep you all posted on the outcome. Oh and yes - I need to take the Pacifica in already ARRRRRGH! 3 days old!!! a hi pitch whistling when tranny in park - possile vacuum leak. - Thank God I bought the extended warranty to cover the 45K mile lease- I may use/need it. SOMEBODY SHOOT ME!!! :screwy:

Thanks again for all your help.