Hi, I've been lurking here a bit. I used to be on the 57-60 forum quite a bit, but the truck in my avatar has since been passed on to my brother. Anyway, I recently bought a 1989 F250. It's the light duty model with the Mazda 5-speed, semi-floating rear end and D44 TTB front end. It has the 5.0 Liter motor. It's a pretty clean and straight Nevada truck and it runs great. It needs some attention here and there. Right now I'm trying to get the AC fully functional. The system is charged and seems to be sealed and I can feel cold air at the vents, but the blower motor isn't working properly. The fuse is good, the evaporator core is clean and the vacuum lines LOOK to be OK as far as I can tell...
Here's my first question: if the resistor pack for the blower motor is bad, should the blower still run on high speed?
Thanks for any help in chasing this problem down...I'm sure to have a lot more questions!
Nice looking truck, you guys live outside the rust belt got it good!
Usually only get "High" with a failed resistor, other problem is the connector to the resistor the connections in it corrode turn green etc and if so blower doesn't work at all or just a little bit regardless of speed selected.
I'd pull the resistor out look at it a minute, tends be reality obvious when any one aspect of one is toast and will no longer function.
Replacement pigtail is also available if find that to be a problem.
Thanks Dan. I already pulled the resistors and they looked a little cruddy, but not really that bad. It's kinda hard to see how those things would even go bad, they're just coils of wire, but I guess they do. I just jumpered the blower motor to the battery and it works fine. So I guess there is a lack of continuity somewhere...now to just find out where. How do I test the resistors? I used my multimeter, set on OHMS and probed both ends of each resistor. I got readings of .005, .006 and .022 I think. Is that the correct way to test a resistor? Does anyone know if those readings are good? Thanks!
Looks like I found the problem. The harness connection for the blower switch is fried!
...unfortunately, I created another one. While I was disconnecting the switch, the sliding vacuum mechanism to operate the doors broke off and a small ball bearing fell out. I have it back together, but I have no idea where the ball bearing came from...
Does anyone know the proper name of the door positioning mechanism in case I need to order a new one?
Thanks for your help Dan!
Last edited by Tumblindyce; 07-21-2014 at 08:22 PM.
Reason: Thanks to danr1
I'm having a real hard time locating the harness side of the blower switch though. There are plenty of blower switches available, but I can't find the female side anywhere on the web. Is there any good reason not to diagram that thing, cut it off and crimp on insulated female spade connectors in its place? It's either that or go the junkyard route...