Electric cooling fan doesn't run with AC on

[willhud]

I have a 1998 34' Georgie Boy Cruisemaster on a 1997 GM P30 chassis. I don't think the electric cooling fan in front of the radiator has ever run. My question is, where can I get a wiring diagram for this system? If I had that I could figure out when the fan is supposed to operate. On other vehicles I have owned, that fan always came on when the AC was on, regardless of engine temp. I have been unsuccessful at locating any of the components ie relay, fuse, fusable link, etc for this system. Any help would be appreciated.

Willhud

[EngineerMike]

Welcome to iRV2!!

IIRC call for the fan is from the ECM, and I also seem to recall it wasn't automatic that the AC turned the fan on (could be wrong on that; but I don't recall if there was a relay. You can run an independent 12V wire w/inline fuse to the fan and test it. I know some who put in a separate line w/switch to invole some aux cooling. Many of those P30 rigs had inadequate grille cutout in the moho body to get full & proper air thru the radiator stack.

[Clay L]

I am not sure when they switched over to the ECM calling the shots but on my 96 P30 the fan was activated by either a pressure switch in the AC system or by a temp sensor screwed into a coolant passage on the engine head.

The fan did not run automatically when the AC was turned on.

There was a relay located on the AC plenum on the firewall of the engine compartment.
There was a fusible link wire off a junction block on the right side of the firewall near the top.

[willhud]

If either of you are right, its possible that the fan has never needed to operate. The clutch fan has always kept the engine temp gauge within a needles width of 180, even on a long hill pulling a 22' pontoon boat. The AC works adequately as long as it has plenty of 134A. (It has a super slow leak that I can't locate.) It works better when the rig is moving than when its stopped. I know I could figure it out with a wiring diagram, but I guess I shouldn't worry about it as long as the engine and I aren't overheating. Thanks again for your help.

Willhud

[TandW]

Willhud, your on it! The electric fans were supplied to ensure enhanced AC operation at no or low speed operation. Six months out of the year you don't need 'em at all. Good luck!!

[oemtech]

Add a swicth and a relay to controll them manually like I did for W Series.

[willhud]

Thanks for the confirmation. That is exactly what I thought the fan was for. I think I will follow oemtech's suggestion and add a switch and relay to operate the fan, since I can't seem to locate the originals. I'll put mine where I can find them.

Willhud

[willhud]

Is it ok to power the fan from another source without disconnecting it from its original wiring? I don't want to run 12 VDC back through something that shouldn't have power to it from another source.

Willhud

[LVJ58]

"Is it ok to power the fan from another source without disconnecting it from its original wiring? I don't want to run 12 VDC back through something that shouldn't have power to it from another source."

You've raised a good question, personally when connecting from a different power source, I would isolate the new 12v source from the original just to eliminate any feed back as you mentioned.

Good luck with your project

[Mr JP]

You could always install a diode in the current power wire to stop any back feed of current. There is always the possibility of a problem when back feeding current when a computer is involved. Good Luck !!

[allegro5]

We recently traded our 98 Swinger, GB. I had a hard time with it running hot! A great 454 Chev, power and good gas mileage! The easy way is to cut the fan wire and run a 20 amp fused line to the right side fuse box! Use a 12 ga. wire and find a place thats only hot when the key is on! I even put in a new fan clutch, and it still was worrysome! allegro5

[KSDP]

Just got home after 300 miles and opened the front to look at the electric fans and neither is operating when the a/c is on. is this something to be concerned about? The a/c hardly works at highway speeds much less at slow speed. Poorest a/c we have had in 5 moho's.

[oemtech]

I would check the fuses and also test the fans by providing 12 volts to the red power wire. You can always add my Fan Switch Mod.

[max49]

As built in 2004 my fans come on for a second or 2 at start up. I also tapped into the line to turn the fans on manually with no ill effect and they still run automatcally. I put and indicator light under the dash to let me know when they are on whether automatic or manally turned on.
However, I disconnected my manual switch for now, not because it caused any automatic problems, but until I put a relay in like OEMy says, it was drawing too much current for the switch I installed. I also had my inline blower for the SP problem on the same switch and between the 2 of them, I definitly need a relay.