Radiator fan issue

ASSISTANCE Electrical & Entertainment Systems
1

Hey.
I seem to be having radiator fan problems, like many ppl have had on this forum.
When I bought the car last year, the fans worked good, but now they do not work at all. The car never gets hot though, even during the extreme heat wave we had last August.
They do not work with the A/C turned on.

I have jumped the wires at the fan switch on the thermostat housing. This turned the fan on when the car was turned on.
I am pretty sure relays and grounds are ok, or else the fan would not have turned on at all.
I am pretty sure my thermostat is open all the time. It takes awhile to warm up, and engine temp goes down on the freeway.

I had an almost-overheating incident once when I lost some coolant driving because a crack in the radiator. Fan never turned on. I am sure it was warm enough to close the fan thermoswitch. I fixed the leak and no more over heating.

I have done much searching on this forum and I am led to conclude 2 things might be defective. The fan thermoswitch, or the ECTS.
I would like to check the grounds, but I have no clue where to look.

What is your input guys and gals?
Thanx for any help you can provide for me.

2

If jumping the “Engine Coolant Temperature Switch” turned the rad fan on, then you are correct grounds and relays are good and the problem is the ECTS, replace it.

It is possible to get enough air flow to keep engine coolant temp. below the 194 degrees needed to close the ECTS, especially on the highway and if thermostat is stuck open, but unlikely on a hot day in stop and go traffic.

The ECTS controls the rad fan relay directly, if engine coolant temp. is at/above the 194 degrees the switch should close and the rad fan will run and if jumping the switch, [grounding the yellow/green lead at the ECTS] turns the rad fan on, then the problem has to be the ECTS.

The rad fan is also controled by the “Radiator Fan Control Module”, [USDM] it will turn rad fan, [and condenser fan] on if engine oil temp. is high, even if ign. switch is off, but would not prevent rad fan from coming on, [when ign. switch is on] even if it was defective.

The RFCM does control the condenser fan relay, [and rad fan relay] so a defective RFCM would prevent the condenser and rad fans from comming on when A/C is on, assuming the A/C works, [A/C compressor turns on and stays on long enough, [not short cycling] for head pressure to go up enough to trigger the condenser fan.

If A/C is working and condenser fan is not turning on, as it should no matter what the engine temp and/or the outside temp. is, do not use the A/C until repairs are made, excessively high head pressure can at the least blow out “O” rings causing a loss of refrigerant or at worst damage the A/C compressor.

If you think your thermostat is stuck open, you need to replace it also. :whisper:94

3

I went out and bought a new OEM Acura thermostat, but have not installed it yet. This is because of the crack in the radiator. I have it Epoxied right now to keep it from leaking. I will install the new thermostat with the new radiator.

I guess I will try to jump the wires at the ECTS, to see if the fan turns on.

Also.
My A/C is currently not working. When I bought the car it did not work. There was a bastard rigged switch in the cabin, going from the A/C Clutch wire then to the ground. The clutch wire is disconnected at the condenser fan relay. I had an A/C tech look at it and he thinks they left the clutch on too long and seized the compressor. It is possible that the relay that controls the A/C compressor clutch is bad. That might be why they rigged the switch up.

The radiator fan did work when I first bought the car, even with the screwed up A/C system. But it dont turn on even with A/C turned on.

4

The A/C condenser fan will not work if the A/C is not working, connecting a switch to keep the A/C compressor on will damage it, if there is no refrigerant in the system and the compressor is turned on, the lubricant, [Ester or Pag oil] is not circulated and the pump will burn out, [seize], even if there is refrigerant and pump, [compressor] is not allowed to cycle it will burn out.

Even if A/C system is not working it should have no effect on the rad fan.:sipread:94

5

Thank you very much.
Yeah, those previous owners should of never rigged up the A/C clutch like that.
Thats ok, I plan on getting a used compressor and clutch and eventually fixing the A/C.
Will alot of coolant come out when I pull the ECT, if I dont drain the radiator partially?

6

If I pull the harness plug off the ECT switch, and jump both wires together, should the Radiator fan run?

7

How much coolant you loose when you remove the ETCS will depend on how quick you get the new ECTS in, just make sure you do it when engine is cold.
Draining coolant to below the level of the switch would be the best way to do it.

Yes, if you jump the ECTS leads, [yellow/green and black] or just supply a ground to the yellow/green at the ECTS plug or at the “Radiator Fan Relay” plug and the ign. switch is in run, [or engine running] the rad fan should come on.

If it does not turn on, the problem may be the relay, supply a ground to the blue lead at the RFR plug, [direct ground to rad fan, ign. switch does not need to be on], if it still does not turn on, check fuse 12 - 15A, [hot at all times] in under dash fuse box, if the fuse is good, check for power on the white lead at the rad fan plug.:corn:94

8

I am a little confused over the location of the ECT on a 93 LS Auto.
Is it the switch on the thermostat housing, or the switch located under the distributor?
I always thought the switch on the thermostat housing was the Fan Thermoswitch, and the sensor under the distributor was the ECT switch.

It was the wire plug on the thermostat housing (green/yellow + Black) that I jumped that turned the fan on.

9

The one on the thermostat housing is the ECTS, if jumping the leads on it turned the rad fan on, then the ECTS is your problem, replace it.:up:94

10

Thank you very much for your help fcm.

I wonder, what is that other sensor? The one underneath the distributor, next to the ECT sending unit?

11

Your probably looking at the “Engine Temperature Sending Unit”, a thermistor that controls the “Engine Coolant Temperature Gauge” it should have just a yellow/green lead connected to it.:idea:94

12

My condensor fan used to turn on when I turned the car off on hot days. But now it never turns on at all. What is the sensor that controls this function? Can I take the plug off it as well to try to jump it and see if the fan starts?

13

The sensor would be the “Engine Oil Temperature Switch”, just like the “Engine Coolant Temperature Switch” it is a simple on/off switch supplying a ground, [when oil temp is high enough] in this case to the “Radiator Fan Control Module”.

Sorry, not sure where the switch is mounted on a G2, it has a 2pin plug with a black, [ground] and a white/green, [output to “RFCM”] lead. :corn:94