Ok so I know almost nothing about Air conditioning systems as personally I don't like them but dad has a 90 F150 with the original AC system and I mean everything original R12 and everything.


Well dad thought he was in either his old 86 f150 or our 10 F150 and turned on the AC. I knew their was no refrigerant in it at all as the hoses leaked it all out but after running it for 45 mins about he said he smelled a burning smell and smoke started pouring out of the vents. He had just met with me and we popped the hood but couldn't find anything burning. He turned off the AC as soon as he told me it was on. The rest of the way home and the driving around he did he didn't have anything burning. For these reasons I am almost sure he burned something up in the AC system.


What could he have burned up in the AC system?
A fan or compressor?
Do you think this was even AC related?


I plan to later swap it out to R134A system but right now I need to know the truck is going to be reliable for him till he can have back mom's car.
Trav

 

The AC won't activate if the pressure is low, there's a low pressure switch for that. I would guess the fan motor is dying, Dads 88 E150 put an impressive amount of smoke through the vents when the blower fan died.

 

I hope it isn't that but it probably is. If it is that hopefully I can get it fixed before winter or monsoon season hits. AC we can deal without but heater we can't.


Trav

 

If your dads truck is anything like my old 94 F150 set up the fan motor is very easy to remove and not all that expensive to replace. Literally four a little screws in the engine compartment and a plug wire to unplug and it's out and the reverse for installation. It was the same on dad's old 88 E150.

 

If I put the trucks heater on and I hear nothing or see smoke can I rule the blower motor as bad? The heater worked flawless all winter long. I have a couple extra ones from parts trucks.
Brother says maybe a rat climbed in the vents but I don't see where it could get in.
Is their a way to test them without installing them?


The blower motor is exactly the same set up as on our 92 F250 work truck and 95 F250 work truck.
Trav

 

Check the resistor pack. It wouldn't be the first time some leaves or other trash got in there and burned up as the resistors do get hot which is why they're in the air duct to begin with.

And yeah it's also possible it could be the fan motor... every motor is made with smoke inside and normally it stays inside (it's built into the windings) but when it gets out you have to replace the motor because nobody sells replacement motor smoke... not even Dorman. You can test a blower without installing it. Pull it out of the plenum, plug it in and run it. Test your current one that way and you'll be able to see if that's the source of the smoke from your vents.

 

Ok thanks for that info Dixie. Guess I will be testing a few things to see what is up. Not sure when I will get to it.
Trav

 

Redneckford, what did you ever find out? I just had the same thing happen to me today and immediately thought fan motor but wanted to check here before tearing into it because with my luck I would get all that apart only to find its a common simple thing that I didn't know about.

 

This gets my vote!!! Even if the A/C compressor exploded there is not much of a way for the smoke (if it made any) to get any place where it could come out of the vents...

 

I didn't find anything out the truck was parked a few days after as it has been having some engine issues that me and dad are dealing with.
Trav