'91 535 IHKA issues

Does anyone have information on how to repair or find a new IHKA-II unit for the '91 535. I do not believe any other years will fit, or maybe late '90 to early '92. The problems with the unit cause the A/C, Recirc., or the R. Defroster not to work. I have ruled out that it is the three switches. Any help would be greatly appreciated.

Thanks,
Tim

Have you checked the IHKA control module?
Look for 'cold' solderings. Resolder and check again. Maybe that helps.

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Originally Posted by shogun

Have you checked the IHKA control module?
Look for 'cold' solderings. Resolder and check again. Maybe that helps.

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Yeah, I took the IHKA unit apart, i did find a Thermistor not properly connected, but i did resolder it, but same symptoms. The circuit board it covered with a red sealant type substance that's nearly impossible to pick through.

unloader relay, preventing the A/C, and the rear defoger to work. Just a wild guess. There is a recent post about "No Battery warning light" that may help you identify this relay.

Javier

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Originally Posted by botardtim

Does anyone have information on how to repair or find a new IHKA-II unit for the '91 535. I do not believe any other years will fit, or maybe late '90 to early '92. The problems with the unit cause the A/C, Recirc., or the R. Defroster not to work. I have ruled out that it is the three switches. Any help would be greatly appreciated.

Thanks,
Tim

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Tim,
I had a similar problem with my IHK (95 though) in that the AC and rear defogger would work at idle but as soon as I got some RPM's they would kick off. I bought a used one using junkyard dog from Wash state for 130$ with a 1 year warranty. The "new" unit fixed me right up (and I had given up on ever fixing the AC as I could not justify spending big bucks for someone to look at that system). In my case, I think the power regulation failed but no easy way to check due to all of the coating on the board.

Scott