My 75 F250 was doing the same thing. My truck had not been started for a long time, like 8 years, when I got it. The heater fan would just howl when I switched it on so loud you couldn't talk over it. Sometimes intrmitent and sometimes non-stop. Then once in a while it would be quiet for 10 minutes and then suddenly start screeching so loud I jumped an almost changed lanes. I tried squirting some oil into the squirrel cage hoping it would hit something. No luck. As a last resort I went into the engine compartment and sprayed the casing of the fan motor protruding from the firewall with WD40. I soaked it with oil. The next day when I turned the fan on it chirped for 10 seconds and has not made a noise since. Its been about 8 months and is still working fine.
sounds like the bearing in the motor are going bad, somtimes the wd40 will cure them by breaking up the old hardened grease in there, other times it will only wash out what is there and make it worse. The heavier oil you use the better off you will be. Worse case, get a new heater motor, not to bad to install. Good luck w/ the wd40, hopefully you won't have to do any more than that.
Don't use WD40 it has salt in it....The name stands for Water Dryer formula # 40 it was never intended as a lubricator just go buy some Rem Oil it works much better and does what it is intended to do Lubricate and you can get it in spray or liquid form.
"WD" in WD-40 stands for "Water Displacement", not "Water Dryer". The functioning ingredient in WD-40 is Mineral Oil - which is a non-volatile and light weight lubricant. When the propellant and degreasing components evaporate, the remaining Mineral Oil displaces air and water making it beneficial for resisting corrosion.
Whether or not there are salts present in the WD-40 (or Rem Oil) solution is of no consequence as long as there is no precipitation or residue that inhibit the product's intended purpose. Salts don't "dry" water, but that would be a positive effect if they did.
Rem Oil and WD-40 are nearly identical in composition. The primary difference is that Rem Oil contains Teflon instead of Mineral Oil. Teflon and Mineral Oil are both corrosion inhibitors and lubricants. They are both petroleum distillates.
While there are plenty of applications where Teflon is superior to WD-40, its subjective to declare that Rem Oil is "much better" for this application. Also, declaring that WD-40 was "never intended as a lubricant" is irrelevant - the product IS a lubricant.
Remington's Marketing Dept has you fooled. Rem Oil works, but it isn't "superior". Rem Oil contains more Mineral Spirits (55%) than Teflon (35%). Mineral Sprits is a degreasing solvent. These two compounds effectively work against each other. Remington put them both into the same can as a matter of convenience to you. They tried to find a balance that does a decent job of degreasing, inhibiting corrosion and lubricating, but the product is superior at neither since the two compounds are applied simultaneously. The best approach is to first use a degreaser and then apply a corrosion inhibitor/lubricant separately.
We're safe to use the WD-40 that we already have on the shelf.
I wouldn't wait too long to replace the motor, my squeaky motor caused an overload in the wiring and took out my entire dash. New motor's are cheap and easy to replace.
__________________ 1974 F250 4x4 Metallic Lime Green, 390-Slighty built, C6 w/lokar kickdown, NP203, Front and Rear 60's w/ Disks, 33" BFG A/T,Dakota Digital Dash, FlowMaster 40's-Dual Exhaust Lots of body work to come...
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company.