So my electric radiator fan keeps blowing the 15 amp fuse (one also for horn), only when it tries to come on with climate control turning on. It will run fine if the engine runs hot and the temp sender turns it on.
I’ve also noticed, sometimes when I turn on or off the climate control, the engine idle blips.
Climate control fan works fine, as does heater.
Where should I start looking?
Could it be the blue relay above master cylinder that controls things?
Sounds like the initial surge of power required to fire up the fan is above the fuses threshold, have you checked what the startup amps are?
Ok, I think I figured it out?
I noticed the fan was a bit harder to turn by hand then I had remembered.
I increased the fuse to 20 amps, turned on climate control, and fan came on without blowing fuse. I let it go, and then suddenly after 30 seconds, it really started to spin faster, the high pitched whirring noise I remember from summer.
I put back the 15 amp fuse, and it works now.
I now remember, during the winter I spilled a bunch of coolant or p/s fluid or something, all down the electric fan area. Maybe something got sticky in there and made it hard to turn? But I thought the fan motor was sealed? It’s a Spal fan.
Still don’t understand why “sometimes” when I turn on or off climate control fan, idle blips, dropping from 750 rpm to 500rpm, like it’s gonna stall, but then jumps up to 900rpm and then back to 750rpm. All the interior lights flicker too when this happens. Feels like ignition is turned off/on for a split second.
It’s a 1988, and I have removed A/C, which is supposed to come on in my car whenever climate control is turned on.
Did some more checks, I made sure disconnected wires going to A/C were insulated so no chance grounding.
I disconnected vacuum to climate control system.
And I disconnected electric fan.
Still get the surge, intermittently, turnung on AND off the climate control fan.
I suspect it’s the fan.
A stalled electric motor has a very big load and tons of Amps, causing a voltage drop in your electrical system.
Put a light, or an other motor or something, in the place of the fan and see if the problem goes away.
I think you’re right. I’ve been reading archives about the issue.
When I first got car, I turned on fan, nothing. I left it on, and a few minutes later, fans started turning. So they were probably seized from corrosion. I’ve also read that I probably burned out Darlington resistor doing that. That explains why my low speed is so high, and maybe why initial draw is so high.
I guess at some point, removing both blowers to repair is my answer, but I will put that off, it looks like a nightmare of a job.
I have done this job, albeit on a XJ, it’s a Royal PITA… But feasible nevertheless.
On my '83 I was shocked to discover that the fan motors were an open design, you could see the windings and brushes. They are mounted in the airstream, so all the dust and leaves and whatnot blow through the motors. On every other car I’ve ever seen, the blower motors are fully enclosed.
I also discovered that the bronze bushings that the shafts were supposed to spin within had seized onto the shafts and broken loose from their housings so the bearings were now spinning with the shafts. To fix that, I drilled a tiny hole through the housing and into the bronze bushing and installed a tiny self-tapping screw to positively prevent that bushing from spinning. Then I was able to free up the shaft itself and get it lubed properly.
Greg,
Do you have the XJ-S Drivers Handbook for your car? Have you read the section on “Environment Control”?
On page 87 of the Drivers Handbook for my wife’s 1990 XJ-S convertible are the following words: “When heating is required the system will not operate until the engine coolant reaches a predetermined temperature.”
It is possible that your climate control system was operating properly when the fans did not come on right away.
Paul