Heater/Fan control issues
Discussion
Fairly common issue and one I have experienced. Step one is to remove the ECU and clean the pins. You may find a couple are black. Clean the male pins with a light 1200 grade dry wet and dry sand paper, and then use a tiny drill bit in you hand to clean the female end. Gently does it. If this doesn't fix the issue, then you will need to send the unit off for a refurb. I will see if I can find whom I sent it to, or have a look at my posts circa 5 years ago. I have a 2000 mk1 and the ECU was located on the backside of the lower shelf near the back of the radio. If you sit in the passenger seat and stick you right hand up the side on the gearbox tunnel and have a route around you should find it.
Wow that looks like it's had some heat around it. You have 2 options. You can bypass the pins by taking either end of each of the pins out of their respective blocks and wire in a bypass. This may or may not solve the initial problem, but I would be concerned that the cause of the heat has not be solved, and/or has potentially damaged some of the components within. You may be able to see any internal damage if you open up the ECU, but as a fail safe I would have the ECU refurbished. From memory it was a fairly low cost job £38 which has lasted me a few years. I have found the emails and I used these guys. www. electroversal.com in Dunstable. Good luck.
^^I too have used Electroversal - - think they have moved from Dunstable, but a Google search gave me contact details.
My heater ECU was turned around by them in about 6 working days - cost around £50 inc P&P.
Similar issues - pin 16 (earth) had gotten so hot it had de-soldered itself from PCB - Electroversal re-soldered it and checked 'function'.
However, the female plug was also heat affected to the point where the original pin was melted into the plug body and the wire core was down to just a few strands - increasing the resistance as well!!l. I bought some female pins from RaceTech, soldered a heavier gauge wire to new female pin then carefully cut the plug body with a craft knife to release the 'old' one and had enough of the female plug to insert the new pin with soldered wire into it. I then soldered the heavier gauge wire to the loom and covered with heat shrink. It must be better, as the plug and ECU are now running (much) cooler. I used some quick-dry epoxy on the female plug to reinforce the area where I'd cut around pin #16.
Nick
My heater ECU was turned around by them in about 6 working days - cost around £50 inc P&P.
Similar issues - pin 16 (earth) had gotten so hot it had de-soldered itself from PCB - Electroversal re-soldered it and checked 'function'.
However, the female plug was also heat affected to the point where the original pin was melted into the plug body and the wire core was down to just a few strands - increasing the resistance as well!!l. I bought some female pins from RaceTech, soldered a heavier gauge wire to new female pin then carefully cut the plug body with a craft knife to release the 'old' one and had enough of the female plug to insert the new pin with soldered wire into it. I then soldered the heavier gauge wire to the loom and covered with heat shrink. It must be better, as the plug and ECU are now running (much) cooler. I used some quick-dry epoxy on the female plug to reinforce the area where I'd cut around pin #16.
Nick
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