Heater woes (solved)

[Umbra]

Last fall I replaced the blower switch and the resistor. Yay! warm air! Fixed!

The wife and I were out for a little ride the other night and it was a chilly. Turned on the heat and nothing.

Knowing I'd already replaced the usual suspects, today I checked all the fuses and installed a new blower fan.
Still nothing. Replaced the relay. Nothing.

I didn't check the motor before I installed it, but I doubt that's the issue. Switches last a long time.

Resistor again?

 

[Umbra]

Lo and behold Oreilly's had resistor...still nothing.

 

[Chris]

More information is needed.

Is it blowing air, just not hot air? Or is the blower motor not working at all?

Does it work to blow cold air?

 

[Umbra]

Blows nothing. No fan.

 

[JEEPCJTJ]

It could be the resistor. It could also be the motor you didn't check or even the new(?) and/or unchecked relay.

There are multiple places your problem could be. You need to get yourself a multi meter and see whats happening in different places when you hit the switch.

Actually where you need to start checking is as close to where the power comes from as possible and work your way out from there. I would start by using the meter to make sure power is even getting to the fuse to begin with, as long as the key is turned on. Then check for power to the relay, that will be what gets sent to the "motor". You can then check if power is being sent to the relay when you hit the switch. Both of the "powers" to the relay may not even come from the same fuse. If all that power is happening, you then need to see if power is getting to the resistor. If there's power there, it's something between the resistor and the "motor".

It's not that hard if you've done anything like this before. If you haven't it may seem harder but it can be used as something to learn from.

I'm not going to be able to post more about this until later this evening but if you need any extra help I could answer then.

Good Luck!

 

[Chris]

I would get a test light and check the connection going into the blower motor when you have it turned to the on position. See if you're getting power to the blower motor first.

 

[JEEPCJTJ]

I would get a test light and check the connection going into the blower motor when you have it turned to the on position. See if you're getting power to the blower motor first.

Since I haven't quite left yet, I'll add this.

This isn't a bad Idea because if the power is getting there the problem pretty much has to be the motor. Oh yeah, the key has to be turned on too to get the power there.

If there is no power getting there, then starting as close to the beginning as possible lets you find out where the problem is coming from.

 

[Umbra]

I just used the test light and there is no power going to the resistor. Sigh. I just assumed that if I replaced the fan switch and the resistor last fall, the problem had to be somewhere after that.

 

[Imapepper]

Power at fuse? Blower should work on high even if resistor is shot.

 

[Umbra]

Pulled the fuses...looked fine but didn't test them. Swapped out the one behind the glove box just because I had some.

 

[Imapepper]

Pulled the fuses...looked fine but didn't test them. Swapped out the one behind the glove box just because I had some.

Use your test light to see if you have voltage at both sides of fuse...throwing parts at a problem will get you nowhere fast and drain your wallet.

 

[Umbra]

Checked the fuses (8 and 11)...no power to either side....mode selector switch maybe?

 

[Imapepper]

You need voltage at fuses before anything else works. Fuse 8 comes from ignition run, Fuse 11 comes from battery. Something doesn't add up...

 

[KCsTJ]

Now you know to start at the fuse and work towards the power source.

 

[Chris]

Now you know to start at the fuse and work towards the power source.

Exactly! This is what I would do.

 

[JEEPCJTJ]

Checked the fuses (8 and 11)...no power to either side....mode selector switch maybe?

You need voltage at fuses before anything else works. Fuse 8 comes from ignition run, Fuse 11 comes from battery. Something doesn't add up...

I don't even have a service manual for my Jeep yet but I'll go with Imapepper's info, fuse 8 will only have power when the key is on, fuse 11 should have it all the time. It's pretty rare for one fuse with power from the battery to get no power while anything else, like the horn or 4 way flashers still work.

Umbra, I'm not sure how you're checking for power. If you're running one Test Lead Cable to each side of where a fuse plugs in it won't show any power even if it's there. If you're grounding one Test Lead Cable and checking only one side at a time where the fuse plugs in with the other Test Lead Cable you will find power on one of those sides, if it exists.

 

[Umbra]

I think I found the problem:

 

[KCsTJ]

I think I found the problem:

View attachment 53335

Yes I think you certainly did.
Where inside the dash did you find that?

 

[Umbra]

I had it blowing but the selector wouldn't switch from heat to defrost etc....will replacing the plug solve the problem?

 

[Umbra]

Yes I think you certainly did.
Where inside the dash did you find that?

Behind the mode selector switch. Had to unplug it to see it.