Cooling Fan not working on 2000 C70 LPT Convertible

SpaceCadetSD · Post by **SpaceCadetSD** » 10 Mar 2009, 22:10

Hi,

I'm used to the cooling fan running for about 5-10 minutes after I shut off my car ... even for short trips/running errands near home.

Just recently (within the past week) the fan no longer runs when my car is shut off.

I read through a few posts and it seems that the problem is usually caused by the relay, or coolant thermostat. I've found the parts on FCP Groton and am sure I could do the repair myself if I knew the source of the problem. I'm not exactly sure how to trouble shoot.

The only information I have is that the cooling fan DOES turn on within a few seconds of turning on my car's A/C ... other than that circumstance, it does not.

Thanks for your help!
Brandon

Post by **MadeInJapan** » 11 Mar 2009, 04:59

Brandon, welcome to MVS.
How is the temperature gauge on your dash?
Is it above the middle mark (3:00)?
If it goes any above that line at all, I would just go ahead and change out your ECT (engine coolant temp) sensor as well as your thermostat- these parts are cheap and good preventative maintenance anyway. If that still doesn't get it, then the more expensive relay. I'm sure there's a way to check that relay but I'm not sure how to do it.
Regards,
MIJ

SpaceCadetSD · Post by **SpaceCadetSD** » 11 Mar 2009, 11:54

Hey MIJ ... thanks for the welcome.

The temperature gauge hasn't changed at all, still goes up to the 3 o'clock position and stays there ... which is why my suspicion leaned toward the cooling fan relay. Would that be you conclusion too, or would you just go ahead and swap the ECT & thermostat as well?

Post by **MadeInJapan** » 11 Mar 2009, 19:57

With this information, I would lean towards the relay- I wish I knew a sure fire way to test it.

Post by **VCA** » 15 Mar 2009, 07:18

MadeInJapan wrote:With this information, I would lean towards the relay- I wish I knew a sure fire way to test it.

The engine cooling fan relay has five terminals. +12V goes in on terminal A1, the fan high speed signal grounds on B1 and the low speed signal on B2. Power for low speed fan operation comes out of C2 and high speed from C1.

Looking at the bottom of the cooling fan relay, from L to R, we have:
C2 | C1 || B2 | B1 || A1

Apply power to A1, and ground B1 and B2 alternately checking for output at the corresponding numbered C pin. If you don't hear it click or don't get voltage from the corresponding pin, it is faulty. If it checks out okay, run the car until it's warmed up, then pull the relay and try again (it may work fine cold but fail hot).

Post by **MadeInJapan** » 15 Mar 2009, 12:22

Actually there might be another way to see if it's your relay or not- your fan should come on when you turn your A/C on.

Post by **VCA** » 15 Mar 2009, 13:50

MadeInJapan wrote:Actually there might be another way to see if it's your relay or not- your fan should come on when you turn your A/C on.

You should be right--it should, if memory serve, kick on in low-speed mode with the A/C on and high-speed when the pressure switch on the A/C high side hits 180psi.

Post by **billofdurham** » 15 Mar 2009, 16:31

The only information I have is that the cooling fan DOES turn on within a few seconds of turning on my car's A/C ... other than that circumstance, it does not.

This was in the original post. Back to square 1? I am baffled too.

Bill.

Post by **VCA** » 15 Mar 2009, 17:58

billofdurham wrote:
The only information I have is that the cooling fan DOES turn on within a few seconds of turning on my car's A/C ... other than that circumstance, it does not.
This was in the original post. Back to square 1? I am baffled too.

Bill.

Wowzers, didn't notice that. D'oh

That's an odd symptom--both are triggered by the ECM, so it's not a "computer can't pull a line to ground" problem for the relay itself [although still check the relay, it may be that the HS contact works but not the LS, or vice-versa]. Also, put +12V (use a test lead with a 35A fuse) on the various fan inputs and see if it runs at both high and low speed. If you have a scanner and have real-time data readoff I'd see what temp the ECM 'thinks' the coolant is and go from there.

jamcrys · Post by **jamcrys** » 26 Mar 2009, 13:40

This for all of people having trouble with your electric fans. You might want to try checking the ground wire on the fan itself, last year I almost pulled my hair out trying figure out what was wrong with mine. With your A/C turned on, disconect the ground wire from the harness and place a jumper from the header to the inside of the harness if your fan kicks on, the ground is bad. I cut mine just after the wiring harness, spliced a new wire in, run it across to around the battery, there is a gound wire already bolted to the inner fender. Unscrewed it , attach new wire with eyelet attached. Bamm!! After spending much time and money. It was something that cost me nothing to fix. Go Figure