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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 07-05-2014, 02:58 PM
Level7 Level7 is offline
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Location: Orange County Ca
 
Join Date: Jun 2014
Posts: 4
Mein Auto: E39 530i
A/C Fan Troubleshooting

Hello everyone, first time poster here. My car is a 2002 530i.

Two months ago I began to have issues with my A/C unit.

Symptoms and Observations:
1. A/C No longer blows cold air.
2. HVAC panel display works (the visual part) when you press any buttons, but nothing actually happens.

I researched the issue on this forum and replaced the Final Stage Unit (FSU) Resistor. Everything went back to normal.

Last week my A/C went out again with a whole new set of issues.

Symptoms and Observations:
1. A/C No longer blows cold air.
2. HVAC panel display is now dead and none of the buttons do anything visually or functionally. Only the back lights for the buttons work when I turn on the headlights.
3. The fan only blows hot air and doesn't stop even after the car is shut off.

I bought another FSU to rule out the last one failing prematurely. It did nothing to remedy the issue. Removing the FSU is the only thing shutting the fans down other then removing the battery or the fuse.

My questions:
Are those classic symptoms of a failed HVAC unit? If yes where would be the best place to purchase a used one? Part number? Is there anything else I should check?

Thanks in advance -

Last edited by Level7; 07-05-2014 at 03:03 PM.
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  #2  
Old 07-05-2014, 03:39 PM
edjack edjack is offline
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Mein Auto: '97 540i 6 speed
Where did you buy the FSU? The dealer part is the only source for quality part. If you bought it on ebay, it's probably junk.
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  #3  
Old 07-05-2014, 06:33 PM
Level7 Level7 is offline
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Location: Orange County Ca
 
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Mein Auto: E39 530i
Quote:
Originally Posted by edjack View Post
Where did you buy the FSU? The dealer part is the only source for quality part. If you bought it on ebay, it's probably junk.
The first FSU I installed was not OEM but the second one was.
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  #4  
Old 07-06-2014, 02:45 PM
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johnstern johnstern is offline
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Location: Cape Neddick, Maine
 
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Mein Auto: 2000 BMW 528iT/5, S/C
Did you check the fuses?
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  #5  
Old 07-06-2014, 03:27 PM
Level7 Level7 is offline
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Location: Orange County Ca
 
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Mein Auto: E39 530i
Quote:
Originally Posted by johnstern View Post
Did you check the fuses?
I looked in the fuse box in the glove compartment and everything was in order. I had to pull the fuse from bank 9 to stop the fan from killing my battery every time I shut the engine off.
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  #6  
Old 07-06-2014, 07:29 PM
cn90 cn90 is offline
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Location: Omaha NE
 
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Mein Auto: 1998 528i 5-sp 140K+
If you have a friend, then swap a HVAC unit to confirm the diagnosis.

There are quite a few HVAC units on ebay.
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  #7  
Old 07-06-2014, 09:15 PM
dannydoo dannydoo is offline
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Location: long island ny
 
Join Date: Jul 2007
Posts: 72
Mein Auto: 540i 6
May need display.It should still work even if STR is out
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  #8  
Old 07-11-2014, 10:05 AM
Level7 Level7 is offline
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Location: Orange County Ca
 
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Mein Auto: E39 530i
Solution Update:

Hey guys I appreciate your help in troubleshooting this issue. I know there are millions of threads about this but I just wanted to post my solution to possibly help new users.

I bought a used hvac control unit from ebay for $80 and installed it this morning. I now have cold air and everything else including the air staying on after shut down is now working as intended.

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Old 07-11-2014, 10:41 AM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
 
Join Date: Mar 2008
Posts: 21,578
Mein Auto: 02 BMW 525i M54 auto 130K
I'll cross reference this thread to one of these, so others can find it in the future ... I'm not sure where it goes, but maybe here?
-How to remove the IHKA heater air conditioning control panel to clean the circuit board (1) & how to check the HVAC (IHKA) sampling fan (1)

See also:
- How to troubleshoot a bad FSU final stage unit (1) and how to build a test jig for your FSR final stage resistor (1) & how to autopsy or repair solder cracks in your blower motor resistor (1) & how to replace your HVAC blower resistor (1) & what FSU is the right one to buy (1) & how to remove the IHKA heater air conditioning control panel to clean the circuit board (1) & how to check the HVAC (IHKA) sampling fan (1) & how to correctly measure cockpit AC temperature (1) & where is the HVAC/IHKA solar sensor located (1) & where to find your low pressure airconditioning recharge port (1) & how to recharge or refill your A/C system for $20 (1) & what refrigerant PAG oil to use (1) & how to diagnose A / C compressor knocking sounds (1) & how to learn about (1) and set up your air conditioning (1) & how to replace the activated charcoal cabin air filter (1) & what cabin filter to buy (1) & cn90's inexpensive cabin filter retrofit (1) & everything there is to know about stinky gym sock AC odors (1) & R134a conversion information (1) & air conditioner compressor replacement DIYs (1) or compressor rebuilds (1) or ac hose rebuilding services (1) & how to remove the trim and bracket holding the MID & HVAC/IHKA panels (1) & how to replace just the IHKA button (1) & how to change OBC MID IHKA KTMP temperature from degrees Celcius to Fahrenheit (1) & how to diagnose lack of HVAC/IHKA heater core heat with cooling system (auxiliary pump) at idle (1)
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Please read the suggested threads, where the best always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need

Last edited by bluebee; 07-11-2014 at 10:52 AM.
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