1986 Chev K20 blower fan problem

[Supertrucker]

First off, this is my daily driver pickup and is not a diesel. It has a 350 gas and an automatic. Members on here have helped me with my diesel Suburban problems in the past so hopefully someone can help here. Lately I have been having problems with the blower fan. One day it just shut off and this has happened before so I figured the fan was shot which it was last time. First I checked to make sure I had power, which I did. Just in case I replaced the fan relay. Next I replaced the fan itself and it still did not work. To make sure I did not get a bad one, I got another one and still nothing. So, I rechecked the power wire at each fan speed postion and everything worked. The ground wire is attached at the very top screw that holds the fan to the air box and the other end of the wire is bolted to the firewall directly above the air box. I completely replaced the ground wire and still nothing. I finally got it to work when I loosened the screw and wiggled the wire, however if I tightened the screw down I lost the fan. It arcs pretty good when you mess with that wire. My next thought was to ground it to another location, but I have the same problem. I plan to replace the steel ground strap that runs from the firewall to the engine block and see if I can produce a better ground to the body. Does the fan ground to any other location? Are there any other grounds in the system such as at the control box? It does work but only if I loosen the screw, but a good bump and the fan is gone. It's very cold up here in northern Minnesota so I gotta have heat. This thing is old, has plenty of rust, 205,000 on the clock, but other than this is very reliable. I sold my diesel so this is all I got left. Any help is greatly appreciated.

[rustyk]

This is of no direct help, but may be of some use in troubleshooting. The HVAC fan's speed is adjusted by way of resistors, individually selected by the speed selector. Typically, these are in the ground circuit ("hot" being supplied by the relay). Ground from the fan motor is routed to chassis ground through one of the resistors (except none for the highest speed). Although my motorhome had an OEM GM engine, the HVAC system is Chrysler...(headlights are Cadillac, and the radiator surge tank is Ford...the RV that Topsy built ...)

Does the fan work if the ground wire is disconnected? If so, that would indicate a short to ground somewhere. Also check the fan operation with A/C on; there's a (very) remote possibility that there's something awry with the A/C compressor clutch wires.

[Supertrucker]

Thanks for the reply, but after some more head scratching I was able to remedy the problem. I know of the resisitors and everything up to the fan worked just fine. If the fan ground was disconnected it would not come on. I finally figured out to scratch the paint off of the new fan housing and bolt it back down and the fan spun like crazy. I discovered if I held the ground wire in the hole using the screw then it would ground. It was a simple problem and I missed this simply due to my frustration and the freezing cold temps.

Thanks.