heater fan not comming on

[862wdranger]

just bought a 86 2wd ranger and everything was great for a $500 truck heat worked (just on high though) but all of a sudden after installing satalite radio and ty wrappin the wires up under the glovebox my heater fan only seems to come on when it wants to not when i need it ie.. in the cold canadian mornings lol.i looked under the glove box to see if i could see any wires that i may hae knocked loose or what not but didnt see anything.i noticed that when i switch from outside air to the inside air if i did it hard enough the fan seemed to kick in but not all the time.i read on her ethe the high speed only could mean the resistor which i will check but need the fan to work first,and there is power since it does come on just not sure of locations to check ,that bout all the info i can think of and detail thanks.

 

[Mark_88]

The most common cause of the heater fan to either work only on high or sometimes not at all is the relay under the hood. If you look at the heater box on the passenger side you will see four wires going into a plastic switch-like connector. What tends to happen on the inside of that connector is the resistors, springs, and connections corrode and fail.

Replacing the switch is usually the best fix for this, and if you have a junkyard (what part of Canada are you in?) near you the switches from the F-150 or later model Rangers are better. These seem to corrode much less than on the older style Ranger for some reason...probably because they angled the box and the switch is no longer in a direct line of road spray...but it could just be condensation inside the box that does them in.

You may need to splice some wires and if you use one with different colored wires (like I did) the connection can be a bit tricky to get them correct. Just don't seal them with electrical tape until you know the fan works on all speeds.

I'm not sure if the radio installation had anything to do with the fan quitting completely, unless you loosened a ground wire or something during the process. But I've not had the same problem after swapping radios and other things in the dash myself...

 

[MAKG]

Pull out the resistor block (it's not a relay) from the blower box under the hood, and LOOK at it. If it's broken, it's plainly visible. This is really the only reasonably likely way to disable all speeds but high.

As for the high itself, a voltage drop test will tell for sure, but you could very easily have banged up the control head right below the radio. It's also possible the blower itself is on its way out. Pull its connector and see if there is voltage across it with the switch on high.

 

[862wdranger]

k thanks i will look at the resistor but mother nature stepped in today and wont allow me to make my way to my truck at a friends house (snow) but i said it does work intermitently kinda when it wants so i dont think anything is broken just loose but i will check for corrosion as for splicing wires i am an electrician so that shouldnt be too hard lol i was more wondering if there was any wires i may have bumpped under the glove box area inside the cab when i was ty wrapping ?thanks again.

 

[Mark_88]

IIRC there is only one wire clip attached to the heater controls and that can certainly be loose. The one that goes to the fan switch on your dash has a two or three wire connector (maybe four depending on your options)...if the retainer clip is broken it can work itself out...and the older the truck the more likely the clips will break off...

If I had pics of mine (I did take some but have since lost the files) I could show you how the different colored wires connect...you might also check the green 30a fuse on it because it may have blown if you overloaded the circuit...

I recently screwed mine up trying to hot-wire a fuel pump...so I'm about to have to swap that out if I can't pull the connectors back through...

 

[Tedybear]

I'd personally pull the radio and check the plug on the switch. Ours did the exact same thing when we changed out the radio. All it took was moving that connector just a touch and everything came back to life.

S-

 

[862wdranger]

ya i was thinkin of trying that as well thanks.