AC/Defrose/Circulation Switch lights all dead

[Gnutz]

I can not get the any of the AC/Defrost/Circulation lights to turn on. I have replaced two times and both units did not work, which leads me to believe the problem is elsewhere.

I have searched tirelessly on the forum for a similar post, but to no avail.

Anyone heard/had this issue, its driving me mad! :eyecrazy

BTW I drive a 1994 530i.

The part number is 1391764, here is a picture of it. http://cgi.ebay.com/ebaymotors/BMW-e34-a-c-switch-cold-525i-540i-530-1-391-764-_W0QQcmdZViewItemQQhashZitem3c9d487b55QQitemZ26033 6810837QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

[Cooljust]

I can see why you're mad...you didn't get what's pictured!:buttrock

[Sneezy]

Are your temp control dials and sliders illuminated?


I can see why you're mad...you didn't get what's pictured!:buttrock

:rofl

[Gnutz]

The dials/sliders are all illuminated.

On a side note... I checked the freon and it is max pressure.

[lovinlyfe4dub]

Does your compressor come on when you press the a/c button?

[Gnutz]

Nope, but the rear defrost and circulation status lights do not turn on, and do not power on their respective functions.

This leads me to believe that there is a wiring problem?

[Gnutz]

Bump

[Gnutz]

bump

[Gnutz]

Bump

[Gnutz]

Bump!!!!

[AquilaBMW]

Does the switch come on based on the operation of the compressor? Anyone know? If so, from what you are saying your compressor does not kick on. Maybe try tracing the issue from there? :dunno.

Are you able to try the replaced units in another car to confirm they were not defective? Checked all fuses and relays?

[Gnutz]

unfortunately, I have not been able to try my unit in another BMW. I am sure the compressor does not power on since the vents do not blow cold air, but since the defrost and circulation status lights are dead, I assumed it was the unit. After trying (3) units and getting the same response ( all lights are dead), I assume it is a wiring issue.

The fuses are good, what are the relays?

I was hoping this was a somewhat common issue discussed/experienced before on the boards.

[marsmann]

Simple things to try:

1. fuses and relays (#9 off the top of head, others too - see manual)
2. Loosen the HVAC control panel and verify that no wires are damaged or melded together from heat. Does your blower work? If some of the other components on the HVAC panel don't work it may be indicative of wiring problems. Check your sliders.

You've already verified the switch and you said that the AC system pressure is ok so that eliminates the pressure switch as a problem and AC button switch. Plus, you aren't getting power to the entire switch including the defroster and recirculation so it appears to be a voltage delivery issue to your AC button or related part.

If you have a 12v tester see if any power is coming to the back of the switch.

Another thing to try - Disconnect the plug to the compressor and see if power is restored to the switch. This test could indicate a short in the system between your switch and the compressor. Sometimes when the compressor is bad or the clutch is seized it won't allow the system to run and shorts the circuit back to your switch. It may or may not include the recirc and defroster depending on how integrated that electrical circuit is.

GL.

[AquilaBMW]

unfortunately, I have not been able to try my unit in another BMW. I am sure the compressor does not power on since the vents do not blow cold air, but since the defrost and circulation status lights are dead, I assumed it was the unit. After trying (3) units and getting the same response ( all lights are dead), I assume it is a wiring issue.

The fuses are good, what are the relays?

I was hoping this was a somewhat common issue discussed/experienced before on the boards.

Common issue or not, we all learn from each experience. First, does the blower work fine and at all speeds?

Do you have a Bentley Manual or the PDF files to guide you? You should check the Compressor and then trace the wiring to the switch. Also, check ALL your fuses - both in the engine bay and underneath your rear seat... do you have a chart to see which fuse does what?

Your relays are the larger plastic things in your fuse box - they are usually Yellow, Brown, Green or White. Some of them power or regulate various electrical operations and systems in your car. Check them out to see if they are the culprit. They are relatively cheap to buy and can sometimes solve the issue.

[Gnutz]

ok, I am going to do all these recommended steps.. Blower works at all speeds, and sliders work as well..

will reply with all results.....thanks guys, really :)

[Gnutz]

I have not forgotten about this thread, just started school and havent had much time to work on the car.

Ive read (like marsmann stated above) that since the AC/Defrost/Circulation buttons are all dead, it may be a DEAD/MELTED wire?

Any suggestions on how to access this. Marsmann, when I take off the HVAC panel screws, the panel only comes forward like 3 inches, barely enough to even look behind the panel.

[530 i]

After I replaced the microfilter I had the same problem as you, the buttons didn't work and no green light for the AC etc. The problem was a loose plug to the black HVAC control module in front of the microfilter, I must have dislodged it. Worth loking at.

[marsmann]

Gnutz,

Wiring could be a problem but probably not likely the cause in your case. If everything looks kosher with wiring, engine bay wiring, compressors, AC switch, etc. and they are all intact you probably have a failure at your IHKR Climate Control module.

it is directly behind your microfilter. pull that baby out, pry it open and check for any damage/burns on the circuit board. Swap/test with a spare unit if you can get one.

If everything else checks out this has to be it. A failure on this module will cause your exact condition with all 3 lights out on your AC switch.

[Gnutz]

I will check out these areas and get back with results....will hope to see burned wires or I will have to get the spare IHKR first..

btw, the AC low and High pressure sides were at 110psi I believe when last checked, is this a normal reading?

[90e30i]

I had the exact problem, luckily I didn't have to buy a new switch since I had another e34 to try parts off of. The problem was the HVAC control moduale. It was corroded inside. Got a new one and everything works great now.

[marsmann]

110psi is way high for AC.

45psi is more normal if memory serves.

[hellspcangel911]

On my car the recirculation button turns on the compressor.. all the switches work, i guess the connectors are just on wrong... never know what the PO did..

[Gnutz]

Well I guess we will never know if it was the IHKR module since I traded in the E34 for $1500 for a Ford Ranger (2003, v6 3.0, 2wd Regular Cab, 56k miles)

[Gnutz]

can you tell if the IHKR is bad just by looking at it? Its seems to look alright

can you tell if the IHKR is bad just by looking at it? Its seems to look alright

[Gnutz]

The IHKR was bad, the AC lights turns on now and cooler air is flowing!!!

But the Ac makes a hissing sound, very loudly....the AC hasnt been used for 10 months, could this be a factor?

if hissing goes away after some use, Ill splurge it on here