A/c light won't come back on after shutoff and restart.

[mossyoaks]

My air conditioning system appears to work fine. On initial start up, all lights come on, fan blows correctly on each speed, compressor cuts on, etc.

But once the fan is cut off or iginition turned off, the a/c indicator light and compressor won't come back on immediately.

After the ignition has been shut off for at least 15 mins., the a/c system turns back on normally.

Fan blows on all settings as it should regardless of the a/c light being on or off.

Is this a microfilter issue, resistor issue or what?

Mossyoaks
95 525iT 175K BostonGreen, roof rails, OEM tow pkg.
95 525iT 125K AlpineIII, Tstars, roof rails
952

[mossyoaks]

Bentley's is pretty vaque on this one.
Any thoughts would be very welcomed.

Chip

[repenttokyo]

what is the duty cycle on our compressors?

[bmwrp8]

Bentley's is pretty vaque on this one.
Any thoughts would be very welcomed.

Chip

I have the exact same problem! but mine the light is on but does that compressor cut...had it for a year and i changed almost everything...compressor, evaporator, e.valve, r.drier, sword , AC brain or the blackbox , AC temp thermostat sensor still the same...now i just live with it...:( if ever you found your solution let me know..and i tried asking around no luck:(

[Fred/Houston]

My air conditioning system appears to work fine. On initial start up, all lights come on, fan blows correctly on each speed, compressor cuts on, etc.

But once the fan is cut off or iginition turned off, the a/c indicator light and compressor won't come back on immediately.

After the ignition has been shut off for at least 15 mins., the a/c system turns back on normally.

Fan blows on all settings as it should regardless of the a/c light being on or off.

Is this a microfilter issue, resistor issue or what?

Mossyoaks
95 525iT 175K BostonGreen, roof rails, OEM tow pkg.
95 525iT 125K AlpineIII, Tstars, roof rails
952
Mine started to do the same thing about a week ago.1st I smell musty air,then I realize it's not blowing cold air anymore. I try to shut it on or off but no luck.
Then I hear a flap open(or close) and I have cold air again.
It just happens when it wants to so I'm looking for a cure as well.
Fred/Houston

[Tiger]

What is your refrigerant pressure when running?

[Ferret]

What is your refrigerant pressure when running?

I was going to say...

Mine used to do something similar to this, and it eventually transpired the A/C gas pressure was approaching minimum tolerance...

Flip on the A/C and the low pressure side would drop out, causing strange behaviour in the controller... AC wouldnt restart after a shut-off.

Dont these systems have high pressure switches as well, to tell the controller that the system is overgassed?

[Tiger]

Yeah, it is called Hi/Lo switch... too low pressure, compressor off... too high, compressor off too.

[mossyoaks]

I haven't had the system pressure checked. Obviously, this is a common issue with our e34s!

I'll follow up later on how it all comes out.

Thanks!
Chip:)



Yeah, it is called Hi/Lo switch... too low pressure, compressor off... too high, compressor off too.

[mossyoaks]

I can't seem to locate where this hi/lo switch goes in Bentley's.

Anybody know?


I haven't had the system pressure checked. Obviously, this is a common issue with our e34s!

I'll follow up later on how it all comes out.

Thanks!
Chip:)

[gale]

The hi/lo refrigerant pressure switch is mounted on the receiver-dryer. On most models the dryer is mounted in the engine compartment, down low, behind the right headlights. You might have to remove the airbox and washer reservoir to get to it.

[mossyoaks]

I was trying to avoid having to have the "a/c professionals" having to get involved. Will changing the pressure switch open up my refridgerant system?


The hi/lo refrigerant pressure switch is mounted on the receiver-dryer. On most models the dryer is mounted in the engine compartment, down low, behind the right headlights. You might have to remove the airbox and washer reservoir to get to it.

[Guapo]

You're probably low on refrigerant. I had the same issue, and in testing for leaks, we put in some UV dye. As soon as I had a bit of coolant in the system, the AC light would come on.

We found the leaks at one of the schraeder valves and the seal to the compressor. I am currently awaiting a new compressor.

Have your system checked for leaks.

[Tiger]

Forget about the switch. Yes, it will blow out with all youre refrigerant and causing you harm. Just hook up the gauge... you can buy a refrigerant can with the gauge and hose hooked up to it.

[gale]

I was trying to avoid having to have the "a/c professionals" having to get involved. Will changing the pressure switch open up my refridgerant system?

Yes, swapping the switch will expose the innards to atmosphere. I'd try El Guapo's suggestion 1st. If you can measure the pressure that's in it now and verify it's not totally empty of refrigerant, then you can probably safely add a can to it. Best to slap a set of gauges on it to make sure it's not overfilled. Any car in the US manufactured after Jan 1993 will have R134a which is cheap and available just about anywhere without a license. You should have a label under the hood stating it's R134a.

If you find it's completely empty and has been at atmosphere for some time, then it's best to replace the receiver/dryer and pull a good vacuum on the system and fill it with X amount of pounds of refrigerant. Do a Google search & find out if you should add a token amount of Pag oil when putting in a new receiver/dryer. Do what Guapo suggested and put some dye in it as well.