Heater only working on setting one

rangie1998 · Apr 16, 2012

Hi All,

The heater on my RRC '92 3.9 only works on setting one, and even then doesn't seem to working very much, unless I switch it to A/C, then all 3 settings work, but no heat.

I've read a few explanations on the net, one of which is that the resistor behind the decker panel has failed, so I replaced this but this hasn't worked.

I've now taken out the dash to get to the heater, is there another resistor that could have failed or am I best just changing the entire heater box?

Any help would be much appreciated.

Thanks

Saint.V8 · Apr 16, 2012

rangie1998 said:
Hi All,

The heater on my RRC '92 3.9 only works on setting one, and even then doesn't seem to working very much, unless I switch it to A/C, then all 3 settings work, but no heat.

I've read a few explanations on the net, one of which is that the resistor behind the decker panel has failed, so I replaced this but this hasn't worked.

I've now taken out the dash to get to the heater, is there another resistor that could have failed or am I best just changing the entire heater box?

Any help would be much appreciated.

Thanks

Had similar on my '93 RRC...

Mine was the resistor you mentioned....

Have you tested the switch in all three positions for continuity??

If the fan motor comes on full song with the A/C set to on, there would be little point getting the motor out, it clearly works fine....

I have the 1992 Schematic for the Blower system, but the forum only allows upto 20kb for pdf's and it tops 1.4 MB....so I have uploaded it to the rapidshare system here...

https://rapidshare.com/files/4280919788/_92_BLOWER.pdf

Hope it helps...

rangie1998 · Apr 17, 2012

Thanks for the response,

I'll have a read through the download you sent me, but my electrical expertiese aren't great so might need to get an auto sparky to look at it.

The fan motors work fine, and have a spare set so have tried these and still the same problem. I also have a spare speed control switch, tried this but still doesn't solve it. I've read somewhere that there is a resistor within the heater box, which could have failed and also someone mentioned magnets within the box can wear down. Decided to tackle this now as was a real pain not having a heater in winter!

West Slope Rover · Apr 17, 2012

You can get to the resistor by removing the air intake grill. On a U.S. model RRC it's in the passenger side vent.

classic kev · Apr 17, 2012

AFAIK there is another resistor inside the heater casing but depending on model and year I'm not sure it does anything. If you do a search you will find a number of threads about it. It is quite easy to check/test the resistor pack under the decker panel. If it is original the chances are it has corroded and/or burnt out.

rangie1998 · Apr 17, 2012

Thanks for the replies, I've changed the resistor under the decker panel with a new one but this made no difference. Will take out the heater box next and see if I can find one inside there, failing that I might just buy a replacement heater box and hope that does the trick!

Heater only working on setting one

rangie1998

Active Member

Saint.V8

Dyed-in-the-wool 100% RR Junkie

rangie1998

Active Member

West Slope Rover

Well-Known Member

classic kev

Well-Known Member

rangie1998

Active Member

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