Cooling Fan Died

[mgb driver]

The fan fail light came on in my 88 Turbo. I've found that it would normally go off when I turned the AC off. I've only driven the car about 12 mi since this has started........... I know it needs to be fixed but just can't find the time. The car has been sitting for a few weeeks, but I'd like to get it out. Any thoughts on how critical the third fan is, or would I be best to not drive it until the fan is replaced?

Kevin
88 Turbo

[g8nightman]

I drove my S4 with only two fans during most of the summer and i didnt have any problem the replacement is about 200 but you might be able to find one cheaper because it is a ford fan Good luck

[Esprit2]

The problem with running one fan short is that the shroud is a one-piece affair, open on the inside (no partitions). If one fan dies, the other two can draw air in the dead fan's opening rather than through the radiator core.

In moderate temperatures and with sufficient forward speed, it may not be an issue. But on a hot day in slow traffic, the loss of one fan will cut total fan effectiveness by more than just 1/3.

Regards,
Tim Engel
Lotus Owners Oftha North

[lotusguy]

Hi,

I disagree, I don't think this effect would be significant, two fans should be fine.
Happy Motoring! ...Jim'85TE

[Esprit2]

lotusguy said:

I disagree, I don't think this effect would be significant, two fans should be fine. Happy Motoring! ...Jim'85TE

Last week I had an Espirt up on the hoist chasing an overheating problem. The center fan was dead. We used paper streamers to trace the air flow and there was a very strong current going in the center opening in the shroud. Not a minor flow around the edge, but a lot of cross-talk. The streamers were 1" wide strips torn from a paper towel. The airflow tore them and drew them into the shroud. I guess I think that's a significant airflow.

Kevin, I'm not saying that having one dead fan would lead directly to overheating. But if the engine runs warm, consider that it's not only lost one fan, but that the remaining two are no longer as effective at pulling air through the radiator as they were when the third fan effectively blocked reverse flow through that portion of the shroud. The test would be stop and go traffic.

Tim Engel
Lotus Owners Oftha North

[Esprit2]

mgb driver said:

The fan fail light came on in my 88 Turbo. I've found that it would normally go off when I turned the AC off. I've only driven the car about 12 mi since this has started........... I know it needs to be fixed but just can't find the time. The car has been sitting for a few weeeks, but I'd like to get it out. Any thoughts on how critical the third fan is, or would I be best to not drive it until the fan is replaced?

Kevin,
Have you actually inspected/ tested the fans to determine that one is defective?

The Fan Failure light only monitors the Fan Relay and the three fuses. Not the circuit prior to the Fan Relay. Not the circuit after the fuse. Not the fan motor itself. If the relay closes and energizes the fan circuit and if the fuse doesn't blow, then the Fan Fail light will think all is well and not illuminate. The Otter switch could fail and allow the engine to overheat, or the fan(s) could fall right out of the car and the Fan Fail light would not illuminate.

The fans turn on when either the Otter switch or the A/C Control switch sends 12 volts to the primary side of the Fan Relay. If the relay's control coil sees 12V, but the relay fails to make contact, or if one or more of the three fan fuses is blown, then the Fan Failure light illuminates. Those are the only two problems that will set the light off.

If you can hear one or more fan running, that rules out the Fan Relay since one relay feeds all three fans.

Check the three 10A fuses in positions 6 (fan 1), 12 (fan 3) and 18 (fan 2) in the fuse box.

If they're all good, then the problem is in the wiring between that fuse and the Fan Relay. That includes corrosion on the fuse spade terminals and/or the socket, a bad fuse input connector, or bad wires from the relay output. The latter is unlikely since each fuse is fed by redundant, parallel circuits from the relay, and each circuit daisy-chains the three fuses. It's very unlikely that just one fuse would loose power due to upstream wiring issues.

If one of the three fuses is blown, that may either indicate a bad fuse or a problem down stream. The probability of a "bad" fuse isn't very high.

A wire may have frayed insulation and shorted to ground... fix the wire.

The motor could have been stalled by debris, even just temporarily. Check to see if the blades are bound against anything and rectify any problems. Finally, the expensive motor could be toast.

Does the fan blade spin freely? If the motor is binding internally or if the bearings are noisy/ sloppy, it's toast. Give it a Viking funeral and move on. If the motor seems good, the problem that blew the fuse may have been a temporary blockage due to debris. You can either use a 12 volt jumper wire to test teh motor directly, or install another fuse and activate the circuit. You can turn the fans on at will by turning the A/C on.

If the fuse blows again, something is wrong in the circuit from the fuse to and through the fan that wasn't obvious in the initial inspection. Find it and fix it. Don't just keep blowing fuses.

Try unplugging the suspect fan and swapping power leads with another fan. If the other circuit's fuse blows, then the problem is in the fan motor. Replace it.

The fan motors are disposable... not really made to be rebuilt. If you knew the root source, they probably wouldn't be very expensive. But as Lotus parts, they're pretty pricey for what you get.

Regards and good luck,
Tim Engel
Lotus Owners Oftha North

[xjsjag]

When I purchased my '89 the fan fail light was on. I got it home and found the center fan to be seized up. I promptly took it out and then apart, cleaned the armature, greased the bushings and bingo I was back in business. Oh yeah, I replaced the blown fuse for the center fan.
Good luck,
Kenny

[mgb driver]

Tim,
Thanks for the input. I've had the car checked and know the fan on the far right (passenger side) is not working. The fan fail light comes on 1) when I turn the a/c on, and 2) when the coolant temp starts to climb. When the shop did the work on the radiator we discussed replacing it at that time (wish I had now) but the service mgr decided it would go a little longer. When I got the car back I was getting some grinding sounds which make me think the bearings are toast. After driving the car a little I've decided it doesn't like stop and go traffic, even in moderate temps with the a/c off, so I will be replacing it as soon as I can.

Anyone know if the old style fan with the orange blades and modular plug will fit the 88 turbo? I need to crawl under the car and look.......... JAE has some fans that may be from G cars at a great price (87 vs 210 for the one we know will fit my car).

Thanks,
Kevin
88 Turbo

[deecee]

Yes, the Fan will work.
Been There, Done That, Still Have the T-Shirt.