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993 HVAC


Blue964
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23 minutes ago, WB997.2GTS said:

ECUdoctor in Miami USA repaired my ECU & alarm modules and they also repair the AC controller. What problems are you experiencing? Warren

No fans, no control over hot/cold air, basically it is doing nothing. What was your experience with ECU doc like--turnaround time?

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12 hours ago, Blue964 said:

No fans, no control over hot/cold air, basically it is doing nothing. What was your experience with ECU doc like--turnaround time?

Turnaround time Sydney>Miami>Sydney was 1 month, considering the amount of corrosion that had to be removed from ECU & alarm, central locking modules. They also removed the drive/block function from the ECU, programmed a new key and supplied a modified DME relay. I recently saw one of their videos where they displayed a new modern PCB that they use in the CCU units upgrading a 30yr design.

Torv at Bergvill is also very good and will answer questions promptly although I understand he only repairs CCU units. I recently purchased his LED kit, HID lightning kit & basket handle LED upgrade, they arrived in 6 days.

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22 hours ago, Peter M said:

Will be interested to hear how you get on.

The checklist available from ECU doc is a great starting point--thanks @WB997.2GTS. There are a few checks in the checklist I'm going to do first to 100% confirm it is not something in the HVAC external to the CCU causing the issues. 

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Think I may have found my problem...if the rear blower isn't working then the CCU shuts all other fans down. Pulled the rear blower relay out and jumped two pins--hey presto, the rear blower comes alive (in fast speed) and sure enough the front blowers also fire up. Then go to test the rear blower in slow speed by jumping two other pins and nothing. So it would appear the resistor/thermo-switch is dead. Sure enough I pull the resistor out and test it with an ohm meter and sure enough it's an open circuit. But wait a minute the thermo-switch hasn't tripped so it shouldn't be an open circuit. A little more investigation and it would appear I have a questionable copper rivet. Give the copper rivet a little tap with a center punch and all is good--the resister now has the resistance it should have to kick in the low speed blower. I'm off to re-install the blower resistor and see if that brings things back to life, or maybe highlight more bloody problems in the HVAC. Just ordered a new blower resistor so my "reconditioned" resistor will do as a temporary measure. Fingers crossed I get out of this with a $25 new resistor.

 

 

resistor 1.jpg

resistor 2.jpg

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Just a quick follow-up, I knew absolutely nothing about 993 HVAC a few weeks ago, but I found the following two on-line resources incredibly simple and useful in diagnosing and fixing a dead HVAC:  https://www.bergvillfx.com/categories/964993-hvac-system-details and https://cdn.shopify.com/s/files/1/2574/6768/files/Porsche-964-993-HVAC-CCU-Troubleshooting-Guide-Testing-Procedure-Complete.pdf?15803118210647334672

So if you have a 993 (or a 964) with a dead HVAC then you might like to go through these guides if you want to save yourself a few dollars by fixing it yourself. 

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