Loaded

WTF is that about? I replaced about a week ago with a 20AMP fuse. I was hoping that if it gets that hot again it will blow the 20amp rather then just melt it away. The new 20amp is holding and not melted yet.

Airflite40

Have you operated the fresh air blower (fuse #17) with the 20amp in there?

worf928

#17 is your fresh air blower. Blower may be heading to pasture. Check current draw on the blower.

On the other hand all the connectors in that circuit can get a lot of oxidation on them. Clean the contacts on the two-prong connector to the blower, the 10-way (or about 10-way) plug to the blower resistor pack (both under the plastic drip tray between the firewall and windshield), and the five way plug to the HVAC head. (And don't ask how I know about all of these connectors and the oxidation that can be on them...)

This of course, under the assumption that the blower's working. Note also that the blower can get power through the defrost circuit relay and the blower relay.

Alan

Fuses not blowing but melting are a clear sign of oxidized contacts between the fuse and the fuse socket. You need to clean the fuse socket. Since you have the new panel type cleaning is a little harder. See if you can buy a contact file - its thin almost like a feeler gauge but with an abrasive surface. Fry's electronics sells them - I'm sure other do also. Do not use a regular needle file or you will spread the contacts too much. Since you have this issue I'd recommend you at least check all your other fuses - pull them and make sure the fuse blades are clean - any that are really blackened - clean the fuse socket too.. same way. You can also use a contact stablizer of some kind after cleaning - 'Stabiliant' is Sharkskin's favorite - I haven't tried it but it seems to be good stuff . Cuts down on further oxidation mainly.

Since you subsituted a 20A fuse and have seen no issues I think your other systems are probably just fine - you may however find the blower runs better now - with less resistance in the circuit...

Alan

Loaded

Well I am total idiot with electrical problems. The fan system actually does run better and it appears to be running just fine. I will check those connections straight away. would a liberal dose of wd-40 and a wipe down work on those connectors?

Pfunde

I don't think you should use WD40 - It's a lubricant. What you need is isopropylalcohol ( contact cleaner ) that removes the dirt and the grease........

Alan

Personally - if everything is working OK except for the fuse issue: I'd leave the other connectors - they must be currently OK. WD-40 is not a good solution and there is nothing you can just "wipe down" - you'll see why when you try - besides it would stink for weeks. Try a contact cleaner/switch cleaner to help clean the terminals and if stabilant is too expensive - just find some other contact stabilizer (radio shack) use it as part of the final cleaning of the fuse socket contacts. I recommend you not use anything else on the fuse panel (like oil, dielectric grease, vaseline etc). Mechanical cleaning is whats mainly required - this is partly what you did when you pulled out the old fuse and put a fresh one in - You ripped off some of the oxidized/corroded material on the socket side and added a completly fresh clean surface with the new fuse ... however it won't last unless you get both sides clean. Also once you abrade the socket terminals (which you will have to do & have already partially done) they will typically deteriorate faster due to loss of the initial surface plating - hence the need for contact stabilizer.

If you don't do this step it will still work fine for a while - then you will likely be back to the same issue - however more corrosion on the socket will make it progressively less able to be effectively rescued - I'd do it now... or ASAP anyway.

Alan

Loaded

WIll do Sounds like a great evening job to do tonight

Barry Johnson

FWIW, I've heard that running a fuse with a higher rating can sometimes cause a fire because of too much being allowed through there... Never had the problem personally, but I did hear that once...

Alan

Barry,
Yes thats quite possible - but this is the other way around a 20A fuse in place of a 30A fuse. With a larger fuse you risk that the wires will just melt or that other connectors not designed for higher current will deteriorate (and possibly melt). It's important that the fuse stays the "weakest link" or else it won't protect anything...

So in general don't upgrade a fuse to solve a problem - you are just creating a potentially much bigger problem...

Alan