Perplexing - cooling fans not working
Discussion
Got a bit of a puzzler here.
My cooling fans are playing up on my 97R Chimaera 500. I had both fail on me on Monday evening, but got home without problems as traffic was light and I was able to keep moving and hence keep the temperature down below danger level (ie <95deg), but it was well above the 80-85deg threshold of the low temperature thermostat and otter switch I have on my car (courtesy of Dave Batty).
Tonight has been my first opportunity to investigate, and I have gathered the following information:
1) My car has the two separate fuses for the two fans - 25A, one sharing the horn.
2) Both fuses appear to be ok and the horn works.
3) I have a fan override switch. With the engine off and ignition on, turning on the fans resulted in a faint click from the relay(s) but nothing else.
4) Visible wiring appears sound
5) otter switch and thermostat were replaced about a month ago.
6) electrical connectors near the fans appeared sound and well seated and are cable-tied to the front anti-roll bar and therefore not in damp puddle near radiator (common fault, I know).
I then decided to pull the electrical connectors apart and spray them with switch cleaner. When I tried the override switch again the driver's side fan came on, but then there was an electrical crackle and it went off again. However, I found that various wigglings of the connectors and switch got it to come on again, so this sounds like a loose connection somewhere. This obviously needs further investigation but its getting a bit late at night to carry on tonight, so that will have to be done tomorrow.
I'm a bit stumped now and would welcome any suggestions on where to go from here. I've got a daily driver, so this isn't ultra-urgent or anything, but I'd really like to get the TVR running for the weekend as I'd like to take it to Silverstone on Bank Holiday Monday for the GT racing.
Thanks in advance
Jon
PS. Bit of an improvement on my "help!" posts of 6 months ago, don't you think? God, I was such a newbie then.
My cooling fans are playing up on my 97R Chimaera 500. I had both fail on me on Monday evening, but got home without problems as traffic was light and I was able to keep moving and hence keep the temperature down below danger level (ie <95deg), but it was well above the 80-85deg threshold of the low temperature thermostat and otter switch I have on my car (courtesy of Dave Batty).
Tonight has been my first opportunity to investigate, and I have gathered the following information:
1) My car has the two separate fuses for the two fans - 25A, one sharing the horn.
2) Both fuses appear to be ok and the horn works.
3) I have a fan override switch. With the engine off and ignition on, turning on the fans resulted in a faint click from the relay(s) but nothing else.
4) Visible wiring appears sound
5) otter switch and thermostat were replaced about a month ago.
6) electrical connectors near the fans appeared sound and well seated and are cable-tied to the front anti-roll bar and therefore not in damp puddle near radiator (common fault, I know).
I then decided to pull the electrical connectors apart and spray them with switch cleaner. When I tried the override switch again the driver's side fan came on, but then there was an electrical crackle and it went off again. However, I found that various wigglings of the connectors and switch got it to come on again, so this sounds like a loose connection somewhere. This obviously needs further investigation but its getting a bit late at night to carry on tonight, so that will have to be done tomorrow.
I'm a bit stumped now and would welcome any suggestions on where to go from here. I've got a daily driver, so this isn't ultra-urgent or anything, but I'd really like to get the TVR running for the weekend as I'd like to take it to Silverstone on Bank Holiday Monday for the GT racing.
Thanks in advance
Jon
PS. Bit of an improvement on my "help!" posts of 6 months ago, don't you think? God, I was such a newbie then.
quote:Haven't had a problem for months actually. I'm treating this as a minor glitch that can easily be overcome, rather than another cooling problem.
You don't have much luck with you cooling system do you!?!
I plan to do the following next:
1) unplug the connector to the otter switch and short across.
2) do a voltage check at the connectors near the fans to see if they're getting power (I have a multimeter, Rev!)
3) do a continuity test on the wiring
4) remove & re-seat the relays. Will probably give a good spray of switch cleaner whilst I do it.
5) Check every connector I can find to do with the fans. Spray with switch cleaner.
I'm confident that the above will pinpoint where the failure is. Failing that I'll have to get it to an engineer, or an engineer to it, but I don't think it will come to that. Well, hopefully not anyway.
>> Edited by JonRB on Wednesday 29th May 12:08
Thanks manek.
Yes, mine are corroded and aren't making good connection - I confirmed this last night. I'm going to clean them up as best I can tonight with either a point file or maybe just an emery board nicked from my other half, then spray them with switch cleaner. Should keep me going for a while.
Ultimately the connectors should be replaced with waterproof ones - I'm sure there must be suitable marine-grade connectors available.
Yes, mine are corroded and aren't making good connection - I confirmed this last night. I'm going to clean them up as best I can tonight with either a point file or maybe just an emery board nicked from my other half, then spray them with switch cleaner. Should keep me going for a while.
Ultimately the connectors should be replaced with waterproof ones - I'm sure there must be suitable marine-grade connectors available.
quote:
Thanks manek.
Yes, mine are corroded and aren't making good connection - I confirmed this last night. I'm going to clean them up as best I can tonight with either a point file or maybe just an emery board nicked from my other half, then spray them with switch cleaner. Should keep me going for a while.
Ultimately the connectors should be replaced with waterproof ones - I'm sure there must be suitable marine-grade connectors available.
Jon
I'm certain you're in the right area with Manek's diagnosis. The same thing happened with my Griff. Once the plug onto the otter gets a bit corroded, the resistance increases, causing more corrosion with the heat and in the end it becomes an intermittent problem, leading to a terminal one. I sliced off the plug and soldered on new connectors, sealing with heat shrink.
Only thing is my two fans are still wired together fuse and can blow a 40amp fuse every now and then.
Good luck
AF
The easiest way to stop the one fuse blowing is to split the supply. So one fan uses the original and the other uses a separate relay and fuse. It can just be pluged into the orignal plugs and takes its supply from the starter motor feed. Or of course you have half speed fans first followed by the full speed when required.
quote:True, but on cars built after 1996 (like mine) each fan now has it's own 25A fuse (by basically putting one of them through the horn fuse) rather than both going through a single 40A fuse. Big improvement.
The easiest way to stop the one fuse blowing is to split the supply. So one fan uses the original and the other uses a separate relay and fuse. It can just be pluged into the orignal plugs and takes its supply from the starter motor feed. Or of course you have half speed fans first followed by the full speed when required.
Well, 4 years later the problem has come back again. Not bad going really.
Looks like I may have to replace the connectors this time though, as even cleaned up one of them makes only intermittent connection.
Is there any reason why I couldn't use crimp bullet connectors (assuming I can get ones rated to 25A) with heatshrink over the top?
Looks like I may have to replace the connectors this time though, as even cleaned up one of them makes only intermittent connection.
Is there any reason why I couldn't use crimp bullet connectors (assuming I can get ones rated to 25A) with heatshrink over the top?
Edited by JonRB on Saturday 23 September 13:23
Personally I don't like them, but I expect they would work for a while. You would be far better off getting yourself some SureSeal waterpoof connectors though, they have a good current density, totally waterproof (so no corrosion problems) and unlike bullet connectors you can actually take them apart without knackering the wires. You do need a proper tool to push the pins in though, so the up-front cost is quite high. But you'll end up using them for everything, so it'll pay for itself quite quickly I reckon.
Fair comment, Pete, but the up-front costs are enormous. I just checked on RS Components and the insertion tool is over £100 
I'd also like to use the car later this evening as we're going out and I wanted to take the TVR although it's not essential. Right now I'm trying to decide whether to risk the current dodgy connectors or go the bullet route.
I'd also like to use the car later this evening as we're going out and I wanted to take the TVR although it's not essential. Right now I'm trying to decide whether to risk the current dodgy connectors or go the bullet route.
Don't remember it being that much. Anyway, rather than bullets I'd rather use some decent spades with a pair of m/f boots to seal it, and solder the connections. Not as convenient as SureSeal for multiple connections, and you have to hand them to make sure you can't plug 'em in the wrong way round, but it'll take the current and be pretty weatherproof. Do make sure you get uninsulated terminals with separate male+female boots though and don't just use those horrible pre-insulated crimp connectors.
Edited by GreenV8S on Saturday 23 September 13:34
GreenV8S said:
I'd rather use some decent spades with a pair of m/f boots to seal it, and solder the connections.
Sounds very much like what's on there already. I wonder if I can salvage the boots and just replace the spades? 
Having said that, I think I may get away with not changing the connectors for now. I've cable-clipped the wires to the front anti-roll bar again and even quite a bit of wiggling doesn't cause either fan to stop working, so I may be ok for now.
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