A/C in turbo e30 discussion

[BMWManiac]

I have everything installed, including a new condensor and dryer. Evaporator is original and I no longer have the aux fan....

I had my system professionally evac'd and refilled....but the A/C isnt cold enough still....I have not been on the highway yet, but I didnt expect it to be this bad, it feels barely cold! I would understand at idle without the aux fan, but even at 30mph, I would expect cool/cold air, no? The place that refilled it did say my fan clutch needed to be replaced, but again, is there any way to make my ac great again?

[downforce22]

i think you need r12 unless you've done the r134 conversion

[BMWManiac]

When I bought the car, it had the sticker that said it was converted to R134a.

I replaced the condenser this past weekend. I don't know how old the compressor, evaporator, or the valve is. I replaced the drier when I did the rebuild, but it is possible that over the past year sitting and moisture getting into the system could have ruined it?

Even with the aux fan removed, it DOES get cool, almost cold when I am below 2k rpms....even on the highway, it wouldn't get cold. In fact, it gets colder it seems at idle. I can feel/see the compressor cycle on/off and I can feel it get initially cool when the compressor cycles on. Once it switches off, warm air.

I am going to replace the fan clutch and go from there. If that doesn't make any change at all, I will have the shop try to evac and refill again. If that doesn't fix it, I'll have them evac it, replace the compressor/evaportor/valve, and drier and pay for them to again refill/evac my system....I'll be sure to post what happens

[Good & Tight]

When I bought the car, it had the sticker that said it was converted to R134a.

I replaced the condenser this past weekend. I don't know how old the compressor, evaporator, or the valve is. I replaced the drier when I did the rebuild, but it is possible that over the past year sitting and moisture getting into the system could have ruined it?

Even with the aux fan removed, it DOES get cool, almost cold when I am below 2k rpms....even on the highway, it wouldn't get cold. In fact, it gets colder it seems at idle. I can feel/see the compressor cycle on/off and I can feel it get initially cool when the compressor cycles on. Once it switches off, warm air.

I am going to replace the fan clutch and go from there. If that doesn't make any change at all, I will have the shop try to evac and refill again. If that doesn't fix it, I'll have them evac it, replace the compressor/evaportor/valve, and drier and pay for them to again refill/evac my system....I'll be sure to post what happens

Sounds like not enough or too much refrigerant, if the compressor is cycling on and off.

[BMWManiac]

On the service invoice, it says they evac'd and charge with 2 lbs of freon....guess they were 1/2 of lb short?

The funny thing today is that the a/c actually got pretty cool today, but doesn't remain cold when going over 2k rpms...at idle, it really cools down quite a bit....not to the point of "cold" but definitely a lot better and if I could get it consistent, it would be fine

[jeffnhiscars]

BMW specs an r134a charge of 900-910gr which is precisely 2 lbs so it sounds like you have the right amount. Keep in mind that the aux fan is there to supplement normal air flow to help dissipate btu's that have been removed from the pass compt. Without that extra air flow that heat is just recirculating and limiting the performance of your AC.

[BMWManiac]

And that makes complete sense to me. However, wouldn't the cool effect be opposite of what I'm experiencing? At normal highway speeds of 45+ mph, wouldn't my A/C be cooler than at idle?

I can sit at idle and feel my a/c getting cooler....once I start moving, the cooling gets worse. How much of an impact does having a bad fan clutch play into this as well? I do need to replace it.

As far as the amount of R-134a, I was referencing the Pelican parts article that recommended 2 1/2 lbs of refrigerant

[Nutzy]

You need to get some gauges onto the high side and low side and quit guessing.

[BMWManiac]

You need to get some gauges onto the high side and low side and quit guessing.

Will do....are the values that I'm looking for in the Bentley or would you perhaps know them off the top of your head?

[Nutzy]

Not off hand, no. I use HR12 isobutane/propane blend in my cars. I charge up looking for 30psi on the low side. High side changes quite a lot with ambient temp.

[jeffnhiscars]

And that makes complete sense to me. However, wouldn't the cool effect be opposite of what I'm experiencing? At normal highway speeds of 45+ mph, wouldn't my A/C be cooler than at idle?

I can sit at idle and feel my a/c getting cooler....once I start moving, the cooling gets worse. How much of an impact does having a bad fan clutch play into this as well? I do need to replace it.

As far as the amount of R-134a, I was referencing the Pelican parts article that recommended 2 1/2 lbs of refrigerant

Your AC should absolutely be more effective at speed.

My understanding of the clutch is that it has an electromagnet and is either on or off. It has no friction plates so if it fails it's just plain dead. If it's cycling its due to your system pressure exceeding the high or low switch thresholds (assuming you have both switches), a faulty wire to the clutch or the temp sensor in the evaporator is causing it too cut out (or it's faulty somehow).

Although I've never heard of this last problem actually happening I have had 37degree air coming out of my vents so it is possible and this could explain why your compressor is cycling at speed since you will never over cool at idle.

I'd do this:

1 def put gauges on it. This is mandatory
2. Check the wiring to the clutch for continuity and try jiggling it with the engine running to see if the clutch cycles. Watch your fingers of course
3 get an infrared gun and check your vent temps at diff speeds. Don't forget to compensate for ambient temp and humidity. What you are really looking for is the difference between the 2. Anything over say 22-23 degrees is passing
4 try disconnecting the evap temp sensor. It's above the gas pedal and I can't recall ifnyou need to pull the console to get to it but it only has a short pigtail and I'm assuming its a normally closed circuit so you may need to jump the connector to remove it as a potential cause. Please check the wiring diagram to confirm this.

Afterthought: I suppose the clutch could just be weak and not stay engaged. You should hear it going in and out though

[DJLimes]

Out of curiosity how much was the recharge for you? Its getting damn hot out here in the valley and I need a/c pronto!

[BMWManiac]

The recharge plus a new high pressure fitting was $120 for 2 lbs of freon.

On a drive of 5 hours, I did have to shut the A/C off because it did get too cold at one point, which is awesome! I just bought a new car, so I haven't driven it really since and I think I still have an A/C leak somewhere. The compressor is original, and probably on it's way out too....will keep all posted, but I say again, it did get cold enough on a long drive!

[jeffnhiscars]

If it's to cold you can just change the temp setting as you would for heat. There's a blend door that will divide the incoming air between the heater core and evaporator.

[BMWManiac]

I did....I think the A/C system just hadn't been run in so long that it took a while to flow into the new condenser, etc....I haven't driven the e30 in about a couple weeks, so haven't been messing with it, but it appears to be fine based on my last drive