diagnose air conditioning problem

[jtanguay]

No A/C.  When I turn it on the engine doesn't even drop in rpm's, but when I turn the blower fan on it does.   If the system needed a recharge, the compressor would still turn on and reduce engine rpm's right? (mainly noise of engine changes)

Any way of getting the compressor to come on for test purposes?  (like jump switch it or something?)

thanks guys, its really heating up

[QuickTD]

The compressor will not engage if the charge has leaked from the system. Also, on the A3 cars the compressor will not engage unless you have the blower on at least "1". If the compressor won't come on with the blower running the charge has very likely leaked out and the low side pressure interlock switch is preventing the compressor from engaging. You could momentarily test the system by bypassing the low side pressure switch. It is usually located on the reciever/dryer, thats the big tank looking thing in the low pressure (larger diameter) line. Be warned, the compressor does not like to operate without a charge to carry around the lubricating oil, thats why it has a low pressure interlock. Don't run it for more than a few seconds while testing. If the AC blows good and cold with the low side switch bypassed the switch may be defective, but this is highly unlikely. I would put my money on a leak...

[jtanguay]

thanks!  i tried the bypass switch and the clutch kicked in.. but no cold air .  I checked for pressure with the bleed valve and it seemed good (but no way of knowing if there is enough pressure in the system)

so very likely there is a leak

time to hook up a peltier system using water cooling

[dieseltech]

yea and about 10 alternators to run the setup, i have a BIG peltier chip, 3 squre feet of surface!!!!! it draws a little over 175 amps at 24 volts dc, and i cant run it long as i have no heat sink big enough. got it from a military surplus auction

[jtanguay]

that is a little bit ridiculous lol.   I'm looking to hook up one 350 watt peltier unit (25 amps @ 12vdc).  air won't be as hot as the regular a/c setup, but will still be a heck of a lot cooler than outside

3 sq foot peltier.... wow.. slap some metal on one side, make it boyant and throw it into the water (metal side out and not touching water) and make a power generator  :lol:

[91 ECO]

I'm figuring that you have r-12 in your system.  If you know someone with a vacuum pump, you can get all of the r-12 out and convert over to r-134.  That's a cheap way to figure out of the system still cools.  Tried that on mine last summer and discovered that the compressor was shot.  Since I live in North Carolina, had to spend the money and fix it.

[shox75]

only way to really tell if theres pressure in the system is to hook up regulators to the high and low side.
But if you had a sufficient amount of refrigerant your compressor would cycle, and should cycle 1-1 1/2 cycles a minute.
Is it possible your clutch is engaged full time (always spinning)? this does happen if your refrigerant is low.
But yea, your are most likely out of it, its very rare for a/c to be still in there for such an old car. You lose 10% a year.
If you get a shop to retro fit it to r-134a, they will recover the r-12 (if any left) and any moisture in there, then do a vacuum for 30min, and the vacuum should hold at 30psi for 10-15min. If it doesnt hold, your system has a leak.
Also keep in mind r-134a will leak where r-12 does not, so to do a proper retro-fit u should change all the seals and drier. However you may be able to get away with just the fittings.

[jtanguay]

wow...  great information guys!  I think I'll just stick with the heat.

One more question.   How much is the most any of you would spend to get a/c working in your car?   Just curious...

[shox75]

umm on a diesel....i would throw out the whole a/c system.
But I guess that depends wat kinda climate u live in.

If you really want to keep the a/c, here is the bare minimum of what you do. This is of course assuming the a/c compressor is functioning, and you've visually checked the a/c system components for signs of leaks.

Go to a shop and get them to recover your system of the r-12, even if you think its all leaked out, there is still some and it cannot be mixed with r-134a.

Then leave the shop and buy the updated o-rings (like $1-2 each), best thing is to remove the old ones, (there is a o-ring at every connection on the a/c system), so you can match the size. The ones for the new r-134a system will be purple (maybe green) and ur old ones black. Replacing them is is not a hard job, may take some time.

Then buy a retro-fit kit from your local parts supplier, can't remember how much but below $30. It will inlclude the 2 fittings u need for R-134a machines, and a bottle of Ester a/c oil. Install the fittings and keep the oil for the shop that will be re-charging system.

You may want to find a spec. sheet of how much refrigerant and how much oil the a/c system will take, to help the mechanic. The spec. is obviously for the r-12 system, but after a retro fit a max r-134a is charged with 85% of the r-12 spec., and the oil is 100%of the old spec.

Go to a shop that will fill it up, they will first vacuum the system and see if it holds. If your o-rings were replaced it should not leek.

By doing it yourself your only paying for the recovery and re-charge. Sorry I can't give you much info. on shop pricing, because I have the convenience of doing it for myself at work.

Good luck!

[jtanguay]

well my uncle can suck the old r-12 out, do a leak test, then recharge with the new stuff

he just won't fix the leak! (too many spots can leak on the car)

so your information is greatly appreciated!  Time to go seal hunting!  :lol:

[rackley]

I literally just took the sawzall to my AC system.  The connection at the condensor snapped when I was moving it out of the way, so I needed a new condensor.  Then I tried taking the hoses off the AC compressor and the nipples on the AC compressor sheered off into the cap/nut on the AC hoses.  So then I'd need new hoses, new compressor and new condensor.  Then I tried taking off the hoses fromthe point where they anchor to that block before they go into the firewall and coudln't break them free from that block.  So I just sawzalled the metal tube portion where it goes into the block.  Bye-bye AC.  Still have the compressor since I need it for the retarded belt relay system though.

Ray

[jtanguay]

chances are I'll probably tear the damn thing out too  :lol:  but its worth a shot with all this hot weather