1997 P30 Cooling fan wiring

[mnppartain]

Hey guys, I had to replace my electric fan today, and I need a wiring diagram so that I can continue troubleshooting. I have looked everywhere on here and the web, but I am coming up empty. The original fan was completely locked up, so I'm sure that the fuse or fusable link is toast as well. The red and black wire leaving the fan go into a much larger loom back into the engine compartment, so I would like to know what wires I am looking for without tearing everything out.  I need to know where the fuse may be, relay, etc. Also, does the fan turn on whenever the A/C is on, or just when the high pressure switch tells it to? And, what part of the engine (sender, etc) turns it on for additional cooling? Any help is appreciated. Thanks guys.BTW, this is a 7.4 MFI

 

[mnmnutswer]

I have a 91 P30 and mines turns on and off only with engine temp. I added a toggle switch on the dash and if I know I am going to pull a long grade I can turn the fan on ahead of time and start the cooling process way before the engine has a chance to heat up. I leave it run till I am well off the grade.

 

[Charlie 5320]

I have a 95, and mine runs with the ac on or higher temp. So it is powered by 2 sources. I've never traced the wires.

 

[Alfa38User]

Are you talking about the fan associated with the heating and air conditioning system or the engine cooling fan as described by "mnmnutswer"??

 

[mypursuit]

My 96 froze up on me once.  Put a load on my voltmeter and I could smell the smoke but never did trip any
fusible links or fuses.  I replaced the fan and it works as advertised.  As stated before it works off of high heat
and AC. Not sure of the AC as I never use it.  It's been awhile but I think as a test I had the engine up to temp
and shut it down and let it heat soak for a few minutes then I restarted and the electric came on briefly then shut
it self off.  Subsequent trips over the North Cascades and it has come on briefly at high temp like it should.

 

[Clay L]

On my 1995 model year P30 chassis the electric fan fusible link was in a box located on the firewall - drivers side upper right corner. Mine blew when the fan locked up. There were two or three other fusible link wires connected to the same terminal as I recall.  I bought the wire at a Chevy dealership. The fusible link went to the fan and then to a fan relay as I recall.
The fan relay was activated by a temp sensor on the head or by a high pressure switch in the AC system.

 

[mnppartain]

Sounds like we're all over the place on this thing as far as the actual wiring. Is there a manual somewhere? I cannot find one anywhere. To answer some of the above questions: There are two fans on this thing. One fan is the mechanical one on the engine. The other is the electrical fan on the outside of the A/C condenser. I have read and read and read online, and it seems as if these things changed from year to year. I have a 1997 Winne Brave, but the chassis book I have is for a 1996. With that said, I can never find parts for the MFI 454 on a 96...only a 97. So, I guess a 96 or a 97 would be close to the same as long as it was the MFI 454. After replacing it I did run the engine with A/C on for a while with a VOM hooked to the wires, but I never saw 12v. Any help no matter how minor is appreciated.

 

[Gary RV_Wizard]

It's a common design for the signal that engages the a/c clutch to also cause an electric-driven radiator cooling fan to come on. That's with factory installed fans - aftermarket fans vary.

 

[frankazoid]

Any help no matter how minor is appreciated.

here is my 2 cents... these are GM electical diagrams. I didn't look at them in details so I'm not sure if that helps, but may be you will get the idea... sorry if it was no help

 

[frankazoid]

also i just googled topic subject and got some info about this on other forums. not sure if links to other place are allowed so i pm'ed you

 

[mnppartain]

This morning I traced out the wires going to the fan. The black was, of course, a ground. The red wire goes to a relay under the dash on the inside. It has another relay just like it beside it, so I removed both and tested them with a VOM. Both of them read the same. (Still no fusible link or fuse). I then turn on the ignition, and checked for 12v. I found it on one of the other 3 wires located on the relay. So, I'm getting voltage to the relay, and the relay looks to be good. The other two wires are pink and green. They both have a ground on them, so it's hard to find where they are going. Any ideas on this? I would assume that one of the wires goes to a sensor, and the other to the A/C. Any help is appreciated.

 

[mnppartain]

I think I finally have it beat. After doing some more testing I have verified that the green wire goes to the coolant sensor on the driver's side of the engine. I grounded the connector going to the sensor, and the fan came on. The only thing left on that side of it is to make sure that the sensor grounds as it should when the engine gets hot enough. The pink wire goes to the pressure switch on the A/C dryer. I took it off and jumped the connector, and the fan came on. It will not come on when the A/C is running, so I am assuming at this point that the pressure switch is bad.

 

[Charlie 5320]

Or it's low on gas. Don't know how much head pressure makes the switch though. Does the air work good? 

 

[mnppartain]

Air works pretty good. I have added a little over a can of refrigerant to get it where it should be. I guess it still could be low, but my gauges tell me that ot's where it should be.

 

[Ryan7361]

I have a 91 P30 and mines turns on and off only with engine temp. I added a toggle switch on the dash and if I know I am going to pull a long grade I can turn the fan on ahead of time and start the cooling process way before the engine has a chance to heat up. I leave it run till I am well off the grade.

I want to do this on my 1987 Establishment P30. Please walk me through how I put a switch on a thermally controlled fan!
Where is this pressure switch I've heard of?