kings1527
05-17-2016, 09:17 PM
Hello all. Just wanted to run past everyone a situation that may start to pop up.
EXECUTIVE SUMMARY:
At times I would have one fan or both cooling fans fail (whether due to high coolant temp or max AC being turned on) without my fan fail light coming on. The culprit was my original 35a circuit breaker still in place and finally giving up the ghost after 35 years. I highly recommend you spend the $3.50 and 15 minutes of labor to swap yours out with a new 40a breaker if you still have the original in place. Watching your temp crawl to 230 on an 80 degree day is a harrowing experience.
EQUIPMENT BACKGROUND:
DMCMW Fan Sequencer
Toby Cooling Fans (about 4 years old)
THE FULL STORY:
I was getting into traffic on a freeway interchange on a day that was about 80 degrees and noticed engine temp go past 220 and to about 230 with my AC on. Highly irregular. As I got out of traffic, I finally turned off the AC and got some friendly high speed air to the front of the car and it dropped to about 180 and I was able to get home safely. Upon further assessment at home, I noticed only one fan came on which surely saved me from overheating earlier. I reached underneath and fiddled with the other fan to see if it was seized and it spun freely. Not long after that, the other fan came on and now both were good to go. But something still wasn't right.
As I tried to troubleshoot it, the best that would happen was I could turn on max AC and both fans would run for about 2-3 minutes and then completely cut out. If I waited 5-10 min or so, they would come back on when I turned the AC back on. Since the problem turned out to originate at the breaker and not at the fan fail socket or relay socket, the fan fail light would never be able to come on. I got inside the electrical compartment and worked my way backwards since I was confident the fans were OK since they'd come on intermittently. I removed the fan sequencer and re-installed the fused link wiring along with a fan relay and got the same results. That ruled out the fan sequencer as the culprit. So then, I disconnected the two wires to the cooling fan breaker, labeled #19 in the diagram.
**Take note that my blower breaker and cooling fan breaker are swapped. My cooling fan breaker is on the driver's side.
Once I disconnected the two wires that go to that breaker (the one on the bottom is brown and orange and the other is black and orange), I jumped it with a 14g wire and that solved all the problems. I went to O'Reilly's and picked up a new 40a breaker for $3.50, wired two ring connectors to everything, and then all was good.
When talking about the cooling system for the DeLorean, it seems it's always about the fan fail module or otterstat, or low coolant but I don't think it's extremely common knowledge about how problematic this breaker can be and/or is starting to become after 35 years. A few threads have touched on how you should remove the 35a and replace it with a 40a but I wouldn't say that nugget of info is so widespread. At times, it was only letting enough juice through to power one fan, sometimes both, and sometimes not at all. We all know how you don't want to overheat the PRV.
The other thing was how my two breakers were swapped back at the factory as opposed to every other electrical "schematic" (BTTF III) that I've come across. Nice to know that once again these cars are as identical as a fingerprint.
Happy Driving
42030.
EXECUTIVE SUMMARY:
At times I would have one fan or both cooling fans fail (whether due to high coolant temp or max AC being turned on) without my fan fail light coming on. The culprit was my original 35a circuit breaker still in place and finally giving up the ghost after 35 years. I highly recommend you spend the $3.50 and 15 minutes of labor to swap yours out with a new 40a breaker if you still have the original in place. Watching your temp crawl to 230 on an 80 degree day is a harrowing experience.
EQUIPMENT BACKGROUND:
DMCMW Fan Sequencer
Toby Cooling Fans (about 4 years old)
THE FULL STORY:
I was getting into traffic on a freeway interchange on a day that was about 80 degrees and noticed engine temp go past 220 and to about 230 with my AC on. Highly irregular. As I got out of traffic, I finally turned off the AC and got some friendly high speed air to the front of the car and it dropped to about 180 and I was able to get home safely. Upon further assessment at home, I noticed only one fan came on which surely saved me from overheating earlier. I reached underneath and fiddled with the other fan to see if it was seized and it spun freely. Not long after that, the other fan came on and now both were good to go. But something still wasn't right.
As I tried to troubleshoot it, the best that would happen was I could turn on max AC and both fans would run for about 2-3 minutes and then completely cut out. If I waited 5-10 min or so, they would come back on when I turned the AC back on. Since the problem turned out to originate at the breaker and not at the fan fail socket or relay socket, the fan fail light would never be able to come on. I got inside the electrical compartment and worked my way backwards since I was confident the fans were OK since they'd come on intermittently. I removed the fan sequencer and re-installed the fused link wiring along with a fan relay and got the same results. That ruled out the fan sequencer as the culprit. So then, I disconnected the two wires to the cooling fan breaker, labeled #19 in the diagram.
**Take note that my blower breaker and cooling fan breaker are swapped. My cooling fan breaker is on the driver's side.
Once I disconnected the two wires that go to that breaker (the one on the bottom is brown and orange and the other is black and orange), I jumped it with a 14g wire and that solved all the problems. I went to O'Reilly's and picked up a new 40a breaker for $3.50, wired two ring connectors to everything, and then all was good.
When talking about the cooling system for the DeLorean, it seems it's always about the fan fail module or otterstat, or low coolant but I don't think it's extremely common knowledge about how problematic this breaker can be and/or is starting to become after 35 years. A few threads have touched on how you should remove the 35a and replace it with a 40a but I wouldn't say that nugget of info is so widespread. At times, it was only letting enough juice through to power one fan, sometimes both, and sometimes not at all. We all know how you don't want to overheat the PRV.
The other thing was how my two breakers were swapped back at the factory as opposed to every other electrical "schematic" (BTTF III) that I've come across. Nice to know that once again these cars are as identical as a fingerprint.
Happy Driving
42030.