Need help w/ A/C

[NoSpeedLimits]

I am so excited about my car's determination to restore itself to new. Ha! In no time I will have a brand new car with over 125K miles ;) Since I have owned my bimmer for a year, I figured out how much she has cost me per month. I pay 155 US for the loan, plus an average of 300 bucks a month for repairs. At 455/month, I should have bought a new bimmer...but, then again, I would have missed out on becoming a amateur BMW mechanic. Plus, I would have been stuck spending my time working on the house and/or preventing my inevitable divorce. I suppose 455/month is a small price for happiness! :) And who knows, now that I am a free man, I may be able to open the area's first independent BMW repair shop.

I apologize for my blabbering, but my mind is kicked into overdrive due to the fact that it's early in the morning and I have just finished pounding a pot of coffee.

So here is what's up...

The other day, me and my new girlfriend (yes, I could not wait...actually, it was the bimmer...she couldn't resist) we were parked in the mall parking lot getting to know each other... well it was about 90 degrees out and no shade… so, I left the car run with the A/C on full tilt. I am not sure how much time had passed because she had my full attention... when I realized that the AC was blowing warm air and there was the faint smell of wet socks filling the cabin air. I glazed over to see a warning message on the dash. Something about overheating... what a coincidence not only was I overheating, but so was my car. I noticed the temp. gauge was pegged and quickly shut the AC and car off. I gazed back over to see her concerned look and thought just my luck, what a great way to make a good impression...damn car! Now what??? I quickly suggested that it’s time to go into the mall.

But, before heading in, I popped the hood and took a quick peek. There was no coolant pouring out, and the coolant level was okay. Good...time to let her cool down. I closed her up and head into the mall for a few hours. On the way back to the car, and am happy to see that there is no puddle of coolant under her. Now, for the real test...will she start?? Stick the key in and she fires right up...great...all is good. As we are heading home I decide to turn on the AC. Although the system is blowing air, the air smelled like a pair of wet socks...so I quickly turn off the AC before my girlfriend is turned off. I open the windows and enjoy the hot sunny ride home….

The follow day, it nice and cool in the morning 55 degrees, I give the AC another chance and this time the smell is gone, but she is only blowing hot air. Other than sounding like ex-wife, what do you think the problem is? And is this something I can check, or should I plan to visit the local stealer?

As always, thanks for your help and taking time to read my posts. Oh-yah, just in case you are wondering, the girlfriend is hanging in there…so, it must not be the car. ;)

TIA,
Steve

[ryan roopnarine]

sounds like yer heater core is dying....that, or your aux fan isn't kicking in. have you checked the coolant level with the car at kalt??? i'd think that maybe your heater core is letting a little koolant spill into the blower area, and resultantly giving the car the smell of wet socks. i like somewhere where its hot enough to live without the defog at this time of year, i'd bypass yer heater core and see if that improves the smell and such YMMV.

[ryan roopnarine]

nevermind, i forgot that your expansion tank is suspiciously close to yer blower motor. it could be that your fan clutch is dead, and when your antifreeze boils out, some is ending up in the vicinity of the vent system. or your aux fan could be not coming on.

[NoSpeedLimits]

Okay, I give up...what is kalt???

[NoSpeedLimits]

Also, I'll need info. on how to test fan clutch and aux fan. TIA.

[ryan roopnarine]

kalt=german for kold

should have "kalt" written on your expansion tank for cold level antifreeze

there is no "definitive" way to test the fan clutch. on my working car, i find that a brisk limp wristed throw of a blade at the 12:00 position spins about -30 degrees before things stop, IE, it should only move about 3 or 4 blades distance when doing this. remember, this has to be done when the car is cold (sitting for at least a couple of hours in the shade) or it won't indicate anything. aux fan can be crudely tested by leaving off your ac :D if it doesn't act up, you can rule it likely broken.

[MBXB]

Check the return line that runs between the radiator and the coolant tank. The hole is pretty small when it get's to the tank. Bruno's site (www.bmwe34.net) has a good pic of the culprit. I expanded mine to about 1/4 with a Dremel. The wet sock smell is probably your microfilter.

[NoSpeedLimits]

OK now that I know what kalt means, yes, I check the coolant level when cold and it is good.

When I attempt to diagnose the clutch on the fan...you indicate what will happen when the clucth is good. What can I expect if it is bad? Will the fan spin freely or not at all, or will some other condition will exist?

Sorry, but I got one more...when you say the aux fan is likely broken if it doesn't act up, what do you mean by act up??? What should I be looking for or listening for???

Thanks for your help.

[NoSpeedLimits]

Just curious, but what will expanding the hole do? Is there a possible connection to the AC malfunction? Or does this fix help to eliminate the wet sock smell???

BTW- I recently replaced my microfilter, and the one I took out looked almost new. Not sure if that helps... I suppose it could have gotten wet in the past few month. I'll pull her out and take a look.

[MBXB]

When the hole gets clogged, you overheat.

[ryan roopnarine]

if it is bad, it will likely freewheel with little force applied to it.

what i meant by act up, if you don't put the ac on, the additional load of heat won't be applied. if you can drive around like this for, say, 500 miles or so, and not experience any overheats or any near overheats, then you know that the heat load that the fan is supposed to be dealing with isn't being cooled off. i would suggest you watch the gauge very closely until you get it figured out. at 3/4 temp, the car should be shut down, as you know what will happen if you don't.


OK now that I know what kalt means, yes, I check the coolant level when cold and it is good.

When I attempt to diagnose the clutch on the fan...you indicate what will happen when the clucth is good. What can I expect if it is bad? Will the fan spin freely or not at all, or will some other condition will exist?

Sorry, but I got one more...when you say the aux fan is likely broken if it doesn't act up, what do you mean by act up??? What should I be looking for or listening for???

Thanks for your help.

[NoSpeedLimits]

Dumb question...how many aux fans are there in an E34???

I never noticed any coming on...so, how are they controlled, thermally or via switch (ie. when you turn on the A/C)?

Also, is there a aux fan fuse that could have blown? If so, do you know where it located so that I can check it out.

[ryan roopnarine]

there's one aux fan in your car. my obc was showing a temp of 101 deg F outside, and mine wasn't coming on because the clutch fan was handling it. it took 5 mins for me to hear an electrickey sound from the front of the car (outside of it of course) and see aux fan operation for the first time in the 1 3/4 years i've owned the car. they are controlled by temp switch, which turns them on automatically with the ac, or when the coolant temp exceeds a set number. scott wm had his aux fan fuse blow, i think its in the main fuse cabinet underhood.

[winfred]

it should come on low with the ac if the resister is not bad, the fuse is 30 amps and in the under hood main fusebox


I never noticed any coming on...so, how are they controlled, thermally or via switch (ie. when you turn on the A/C)?

Also, is there a aux fan fuse that could have blown? If so, do you know where it located so that I can check it out.

[NoSpeedLimits]

I just checked a few items and am hoping you can let me know what to check next.

1. the #25 (30 AMP) fuse is indeed blown.
2. the #29 (7.5(I think) AMP) fuse is good.
3. the clutch on the fans is good (per Ryan's spin test).
4. the aux fan spins freely
5. started car and AC, and the aux fan did not turn on.

what next...

[ryan roopnarine]

if the aux fan is supposed to come on automatically with the ac, i think i might have a problem. mine only cycles on and off with the ac on, and it generally takes some idle time for it to start when parked.

[NoSpeedLimits]

Also, is it possible that my refrigerant blew out when I overheated the car? Someone at work indicated that I may have overheated the compressor and as a result lost my charge...therefore, explaining why there is no more cold air. If this is the case, then I suppose a trip to the local repair shop to have my system re-charged would solve my ac problems, right?

[ryan roopnarine]

um, ok. i doubt you'd have lost all yer refridgerant from an overheat. if you can get the green light to illuminate on your a/c button, you likely have enough refrid. to get the compressor to function. you have a 94, i would think you could go get a "free" ac check somewhere, or buy one of the r134 refills from walmart that has a gauge on it for 17. your hcv might be dead if you're not getting any cold air.

[MBXB]

Make sure your cooling system is OK first. Will it run to full spec without the AC ON?
If your car cooling system fails without AC, then it surely won't handle the added load especially in summer. I dciked around with what looking for a stuck thermostat, bad water pump etc, and it ended up being that dumbass return line and a recalled coolant cap. I'd replace the cap stat.
Then proceed to debugging the AC system.

[NoSpeedLimits]

I agree, I do not believe that I lost all of my refrigerant, but enough to cause my AC to stop blowing cold air. I will be stopping by a shop to have it checked out. As for the AC button, are you saying that the green light indicates that the compressor is operating? If so, then that is cool(no pun intended)...because my light was the right color. I would have guessed that the green light confirmed power to the compressor...but I am learning.

[ryan roopnarine]

if you get NO cold air whatsoever, you likely don't have enough freon for it to start up. if the compressor doesn't want to operate, that light won't come on. the comp has provisions so that if there isn't sufficient refrid. it won't operate, and the light will (through a kind of feedback) not illuminate. my ac has to operate most months of the year where i live, and i find that sometime the ac has to have 5 or 6 seconds (or whenever its been stressed before turning it on) between on/off before the light will illuminate (and no, the switch isn't dirty). ild make sure your cooling system is ok first though. hate to hear about a blown headgasket on a v8 on the board.....


I agree, I do not believe that I lost all of my refrigerant, but enough to cause my AC to stop blowing cold air. I will be stopping by a shop to have it checked out. As for the AC button, are you saying that the green light indicates that the compressor is operating? If so, then that is cool(no pun intended)...because my light was the right color. I would have guessed that the green light confirmed power to the compressor...but I am learning.

[NoSpeedLimits]

Do you know what the full spec is? I don't believe it will overheat without the ac, but I can certainly check.

About 4-5 month ago, I replaced water pump, thermostat, and bled the system without any problems. And the return lines were not blocked. So I do not believe there is an issue with the coolant system.

I am leaning toward the aux fan as the culprit of my overheating, I just need to figure out what to check next. In a little bit, I plan to pull the plug on the temp switch and short the two circuits. So, I'll report back with my findings.

[NoSpeedLimits]

Ha, ha, ha, are you trying to jinks me...I sure hope that my head gasket is not blown. The car is running just fine and there is no visible signs of smoke pouring out the exhaust.

Since my green light works, I was wondering if the temp controls in the car effect weather or not I get cold air in the cabin. In the summer, I usually leave both dials cranked all the way down it lowest setting of 64 degrees.

[winfred]

no green light, it's blue
if the aux fan doesn't come on with the ac the resister is most likely dead
the resister is on the 4:00 position of the aux fan
if left to idle long enough the fan will kick on high but most of the time this blows the 30 amp fuse due to high starting amprage
if the aux fan is not running with the ac lo speed performance will suck
you need to splice in a new resister 64 12 1 388 069 $36 dealer, yellow butt connectors or much better solder and shrink
sometimes the light on the switch comes on with or without freon

[NoSpeedLimits]

I think someone changed your LED...I mean the last time I visited the eye doctor, he told me I was not colorblind... ;) only kiding... mine looked green, but I didn't really take a close look... Anyway, thanks for the answers! Ever since I owned this car (1 year and counting) my ac has been less than impressive. It worked... but anytime I got in another car I always noticed that their ac worked so much quicker than mine -- much better response time.

[JonE]

I just went through the overheating issue with my 535i. Two issues in my case; 1. No cold AC even though blue dash light on and aux fan came on and ac compressor clutch engaged. System was low by over 2lbs of R12. You have newer refridgerant, very easy to check and refill with the guage kit Ryan suggested. 2. My overheating was due to poor fan clutch operation. Replaced this and now when the engine is hot the clutch fan blows SIGNIFICANTLY more air. The bad fan clutch was freewheeling when the engine was warmed up. It should blow alot of air. You might want to check this too if car still tends to overheat when ac is off and car just sitting, like in heavy traffic. Good luck.

[ryan roopnarine]

looked at gale's page about the ac resistor, didn't realise that he had made a page about it. the resistor he specifies for the chrystler cordoba is .5 ohm, but i can't find wattage of it anywhere. autozone has one in stock for $3.19, same model number as he mentions :D i might try that as a replacement.

ps.......later found a spec for a performance version of the same resistor. the performance one is 200 watts. if this is the case, i'd assume that the standard one would be at least the 75 watts of the original :D gonna try this route.

[winfred]

most good sized ceramic aux fan resistors will work, just don't put it near meltable stuff it gets real hot. the motor running on high draws around 25 amps, starting amprage in high is around 55-60 amps, that's why it starts off in low at around 25 amps. the 30 amp fuse can handle the 50+ amp start a few times because it only pulls it for about a half second or so. mount the resistor in the airflow to keep it and everything around it happy