Topic: A/C Blowing Warm

[Grundar32]

A/C systems need to run at a certain charge/pressure . It cant be too high or too low or the performance will suffer. and depending on the system any of the compontes could be the cause ive seen clogged condensors externally(with bugs and dirt ) and internally (possible pinch or dent in lines) evaps do have a nasty habit of small leaks along with the possibility of clogged orifice tube /exspansion valve. you can get away with not bleeding the whole system down and weighing the charge with a set of a/c gauges and little by little adding a small amount of refrigerant untill you get  aprox 28-30psi while the vehicle is running compressor on idled up to about 2000rpm at the same time after each addition of r-134a give it time to equal out in the system and check the temp comeing out of the vents keep this up until you have the desired temp or the temp starts to rise in whick case you've gone too far there are other issues with the clogged orifice that can also arise but this has always been a good starting point

[Grundar32]

oh and those valves you say are leaking can be replaced they are basically the same type as a tire valve stem but a diff size .. you should be able to get them at a auto parts store

[KS98TJ]

My uncle and I use the Interdynamics recharge kit pictured below to do A/C work.  He's a dealership service manager and been doing this stuff for a living for 30 years.  He's even got the "sniffer" probe to detect leaks- über cool!  It costs less than $20 and works well.  Best of all, it keeps you from overcharging.

I had the low-pressure switch blow on my Jeep this past summer about a month after I had a shop install a new compressor; the old one died.  Of course, I then promptly moved back to VA!  The good news is that my uncle helped teach me A/C and we solved it with a new switch and a couple cans of R-134a.

Since it doesn't sound like the Chevy's system has been opened to the atmosphere and merely lost refrigerant instead, you should only need to add refrigerant.  Be careful of using the oil/refrigerant mixes too often.  You can get too much oil in the system.  The other thing to be careful of is overcharging.  If you overpressurize the system, it won't cool properly since there's too much overall pressure in the system to allow for proper expansion; it's the expansion at the orifice tube that provides the cooling.

Good luck!  Even if it is still winter...  :wink:

Interdynamics EZ Chill Quick Charge R-134a Charging & Measuring Kit
http://www.id-usa.com/product.asp?CID=27&PID=45

[Grundar32]

hey thats nifty i havent seen those  :D

[Jeffy]

Well, I like I said, it doesn't blow cold.  The switch low-pressure switch isn't bad since I can bypass it and turn the compressor on.  When full the system does work but isn't that cold.  I still think it's the expansion valve. I've already got a gauge/filler.

[Grundar32]

thats the most common and easy to replace .. unless you have somthing to recover the 134 you'll have to get new stuff .. maybe check to see what the charge weight is for that vehicle and go by that instead of pressure ... just my 2 cents  :)

[Jeffy]

thats the most common and easy to replace .. unless you have somthing to recover the 134 you'll have to get new stuff .. maybe check to see what the charge weight is for that vehicle and go by that instead of pressure ... just my 2 cents  :)

Hahah, that's not a problem.  it all leaked out of the dryer in a few weeks.  Can the expansion valce be cleaned?  I'd assuming since the system was dry for an extended period of time any coolant or oil might have dried on the screen.  I'll probably have to replace the dryer too.

Stupid thing is this all started because the Dealer replaced the radiator once and had to drain and refill the system.  Then my parents didn't take it back and complain even when I told them to 3 months after the work was done and the AC leaked out.  It's been a few years now.  What a PITA.

[Grundar32]

guess you could clean it but i dont think they are more then a few bucks .. if the dryer has been exposed to air/moisture it too "should" be replaced but ive gotten away without doing so, but if it's leaking then thats another problem :(  and if it's all drained anyway change out that schrader valve on the inlet and try to get a vaccum on the system before charging again

[Jeffy]

Never priced one but if it's cheap then it would be better to just replace it.  How much would it cost to vacuum it?  For that matter a recharge?  If it's under $30 then it's not a big deal.

[Grundar32]

if you know someone with a pump ... a shop will charge time+134 most ive seen per # is $9 then 1/2 hr shop rate is what we would charge looking more around $60 for this area but im in CT  :(

[Jeffy]

How crucial is it to get all the air out?  Can it be done without the pump?

[Grundar32]

if your having performance issues anway i would say you would want to get some vac on it before recharge some systems are more touchy about this then others... i was talking to a friend of mine about this thread and he had told me he used a pump out of an old fridge.. he McGyvered it together and it still works fine for him lol

[saylor240]

yes you do want to vacuum system .jc witney has cheap vacuums and for automotive its worth having one .....you want no atmosphere in your system if you want it to last .........yes dryer should be replaced if opening system .....yes orifice can be blown out best to use dry nitrogen .....in fact you should blow out all lines with nitro if possible once sytem is reassembled charge sytem with 50lbs dry nitro leave overnight and see if you still have leaks.then pull deep vacuum.....time is not most important .to see if you have moisture in system (killer on compressor and freezes orifice) pull vacuum 15 min drain oil from vac put in clear glass .is it cloudy? if yes put new oil in vac and pull down another 15 min ...still cloudy ? keep repeading if by the fourth or 5th vacuum still cloudy you have leak or there is major water in system witch will cause ac to not blow cold even if fully charged ...once you have all moisture removed .the proper way to charge a ac system is by manufacuer specs IE: THIS A/C UNIT HOLDS 3.78 OUNCES  you can use a digital scale or if you can find one a dial a charge..but remember to account for hose lenght.there is alot to an a/c system sometimes its worth the 100 to 200 dollars to fix  :shock: