AC not working..

[etlsport]

I did a search, didnt see any issues like this one.. here goes..

the other day I drive like 20 minutes, park the VX, turn the key to ACC to listen to the radio with the engine off, my friend shows up, i start the VX and take off. i realize its getting cold.. look down, indicator lights for the AC controls are all off, i try hitting a few buttons, nothing worked, tried changing fan temp from auto to the manual settings.. still nothing, got out, checked all the fuses, nothing.. turned the vx off, pulled the key, started it back up, worked fine

few days ago, get in the vx, start it up after sitting overnight.. no AC lights again, shut it down, started it back up, works fine again

earlier today, vx had been sitting for maybe 2 hours, same thing

havent noticed a pattern in when it happens, just randomly it will be like i have no power to my AC, the backlighting still works fine when i turn the headlights on, just no indicator light to tell me which mode i am in (defrost, feet, dash etc) and nothing works until i turn it off and turn it back on

could this be the resistor behind the glove box? i thought all that did was give you no control over fan speed

[Chopper]

I hate electrics:madp::madp: This is gonna suck in a few months. Better get techin' Mr. Engineer. You know where your meter is:rolleyes:

[HotFlyer]

Is the compressor turning off and on? Or is the problem just the fan.

Howard (0761)

[Joe_Black]

Compressor relay may be faulty, have seen that before with other vehicles. One of my current 300D's did this until replacing the relay and its socket which was corroded pretty bad. Works like a champ now.

Left unchecked it could freeze-up and do some damage which translates to $$$.

[tom4bren]

Intermittent electrical problems are the worst thing to try & trace. I'm guessing that with all of the work you've done behind the head unit, a connector may have come loose behind the dash. Since none of the fuses were blown, that would be the next thing I'd check.

[WormGod]

Wow, people using A/C? I am still using my heat! Heh!!! Though, I can't use A/C in my VX with my S/C cause it causes too much overheat anyways. :(

I will agree it doesn't sound like the unit as much as it does the electronics/wiring. And sadly, that is where I draw the "dumb" straw. I heard of a similar problem with a buddy who has a VW. His auto temp control had a mind of it's own. A visit to a VW dealer revealed and solved his issue. I never heard what the issue was though. Pesky dashboard poltergeists. :(

[etlsport]

haha its not just the AC.. I cant get the climate control to do ANYTHING when it does that, no heat, no AC no fan no nothing.. I looked through the electrical troubleshooting manual, I'm going to check the fuse for the blower controls again, then like joe mentioned, the relay seems that it could be a likely culprit from the wiring diagrams. I need to get behind my dash soon anyway to take care of a few other little electrical gremlins, at least i know what the problems with those are. at this point i have pretty much completely re-wired the VX stereo, and lighting, so i just have to hope i labeled everything correctly so it will go quickly!

[etlsport]

ok got in there finally.. saw no loose connections, so i went into the fuse box.. got the vx to start with no ac/heat controls at all, so i started pulling fuses and re-inserting to see if that would cure it.. nope

moved on to relays.. as soon as i pulled the relay marked "heater" in the engine fuse box i got all sorts of fun noises.. put it back in and the AC was working.. so ill see if maybe it was a bad connection.. if it happens again ill replace the relay

[etlsport]

still happening.. called up merlin to order the relay.. $26!! i was expecting like 5 bucks.. oh well, should be waiting on my doorstep when i get home so hopefully that'll solve the problem

[VehiGAZ]

I'm gonna guess that the new relay will solve your problem. There are not really any other components that would cause the behavior you've been seeing.

Some relays are $5, some are $50. There's one relay on my 928 that costs about $125 last I checked. Guess what? I'm not carrying a spare of that one!

[etlsport]

:cryb: the new relay actually made it WORSE!

before the new relay, the AC would work 100% of the time on a cold start
about 33% of the time after 1-2 hours of sitting
about 60% of the time after less than 10 minutes of sitting

the new relay works 0% of the time on startup.. i have to go under the hood and pull the relay out and re-insert it to get ac controls ever.. which was unfortunate since last night was cold and rainy = lots of foggy windows

i guess ill put the old relay back in for now :_confused

[etlsport]

took the new relay out, put the old one back in.. its working 100% of the time now.. (so far) im confused but ill take it:_confused

[etlsport]

well the AC is acting up again..

it comes on when i turn the key maybe 50% of the time.. 100% if i hold the key in ignition position for a second longer than necessary

BUT now the controls have started randomly losing power..

i dont even know how to test to see what could be causing this problem.. anyone have any ideas?

would it do any harm to bridge the relay with a straight piece of wire to see if the ac stays on that way? that would rule out the relay or at least that branch of wiring

[VehiGAZ]

would it do any harm to bridge the relay with a straight piece of wire to see if the ac stays on that way? that would rule out the relay or at least that branch of wiring

You can do that, but make sure you know which poles to bridge.

Are you fully charged with refrigerant? If you are borderline, that could possibly shut the A/C off (under-pressure protection switch).

Good luck!

[kobie]

I am by far no mechanic but I went through the same thing- my relay had been acting up for at least a year and a half. I'd say just replace the relay and be done with it. As hot as it is in TX at one point I was willing to pay whatever it cost (short of going to the dealer) to get the replacement.

[etlsport]

I am by far no mechanic but I went through the same thing- my relay had been acting up for at least a year and a half. I'd say just replace the relay and be done with it. As hot as it is in TX at one point I was willing to pay whatever it cost (short of going to the dealer) to get the replacement.

i did replace the relay.. ordered it from merlin.. 30 bucks.. made the problem worse lol

vehigaz, thanks for the lead.. i took out the relay and directly connected the 87a to the 30 terminal.. ac controls worked fine and the ac blew COLD... but after that i couldnt re-create the problem with the relay in place.. so could have just been a fluke

[etlsport]

drove down to MD last night.. all day i couldnt get the ac to stay on for more than 10 minutes at a time. so i removed the relay and just bypassed it with a wire, the ac worked perfectly all trip, except that when i stopped for gas the ac stayed on with the key out of the car ;Db; i guess its possible that the new relay i ordered was bad, but im more leaning towards the fact that there is not enough voltage getting to the relay to activate it.. but i have no idea what would cause that

on a side note.. since i installed my high output alternator, the charging system indicator light has been on.. after about 40 miles of driving with the ac relay bypassed.. i noticed the light had turned itself off :_confused

[tom4bren]

Sounds like you fixed it till it was broke.:)

[etlsport]

Sounds like you fixed it till it was broke.:)

quite possible..


anyone have any ideas... here is what i know..

AC control panel will not power up at all when the car starts (ie no lights other than backlight, pressing buttons does nothing) if the ac does start with the car.. it will usually stop functioning within 5-10 minutes.. most often when i hit the gas

If i get out and remove the "heater" relay under the hood and replace it, the AC works fine, and blows cold... when I bypass the relay completely (connecting the 87 and 30 terminals with a wire) the ac works fine and blows cold when this relay is bypassed, the controls do not turn off with the ignition

If i get out and remove the "ST CUT" relay under the hood and replace it, the ac controls will turn on and function properly.. ac blows cold.. if i bypass that relay (87a to 30) the ac works fine and blows cold. it turns off with the ignition.. but will not turn back on unless i remove the wire and put it back in again

i have changed the AC fuse under the hood as well as the dome light fuse in the cabin as per the workshop manual.. still no luck... starting to run out of ideas :_confused

[etlsport]

think i found the problem...

I replaced my alternator with a 150 amp one.. the new one has a different style voltage regulator than stock.. this one causes the charging light to be illuminated pretty much all the time... looking through the elec. manual i found this..

http://www.vehicross.info/gallery/data/500/blower_control.jpg (http://www.vehicross.info/gallery/showphoto.php?photo=11985)

only thing im having trouble wrapping my brain around right now is why bypassing that relay would make a difference.. since if the voltage regulator wasnt giving the proper output.. there would be no voltage to pass through the relay when activated... sigh..