98 XJ A/C Heater Blower Motor Resistor Help

[Sandman4182]

I am trying to fix my A/C Heater control it is currently only running on high. I have replaced the A/C Heater Blower Motor Resistor and it is still only running on high. I went to the donor and retrieved the whole control unit and changed that. Whats the next step in diagnosing this issue? :confused:

[4.3LXJ]

Did you replace with a new resistor or used from the yard?

[Sandman4182]

I replaced it with a brand new one.

[4.3LXJ]

I woud suspect that the one you used is not good. The only way I could prove it would be to check to see if you are getting current from all wires on the fan speed selector switch. You can do that with a test light. If you are, the resistor is bad.

[Sandman4182]

The only way I could prove it would be to check to see if you are getting current from all wires on the fan speed selector switch. You can do that with a test light. If you are, the resistor is bad.

I hate to sound like a idiot but how do you do that. Im not very good when it comes to heating and electrical. :bang:

[nickxj94]

Check the connection on the back of the switch? Mine is melted and stuck on high

[4.3LXJ]

I hate to sound like a idiot but how do you do that. Im not very good when it comes to heating and electrical. :bang:


Check the connection on the back of the switch? Mine is melted and stuck on high

That is kinda of where I was heading. The switch and connection is notorious for getting hot and failing. The way they have that engineered, it pulls too much current through that switch on any speed. The way you do this is to get the test light. Then put the clip on a good ground. Then stick the probe into the individual spades on the connector, or plug. If you switch the switch you should get different pugs hot as you change the switch. If not, then you need to go back to the switch and connection there. If you do, the resistor is bad.

[clawdog60]

Where is the location of the blower resistor?

[4.3LXJ]

On the heater/AC housing just under the glove box

[oderdene]

visible from underneath

http://i85.photobucket.com/albums/k48/blackbeast1/blower%20motor/IMG_2028.jpg

thing with numbers on it 8956xxxxxxxxxxxxxxxxxxx

[clawdog60]

Anyone know the temperature rating for the thermal limit on the resistor assembly. Some furnaces used to use them some years back. Might turn the resistor upside down upon re-install to keep some of the direct heat off the element and still have some protection or run a higher temp. element (so long as you don't have wiring,switch,motor ie. issues)

[clawdog60]

My assembly shows no signs of overheating but the thermal element is open. Could even be some residual heat from the resistor after vehicle is turned off burning out the element over time?

[oderdene]

factory fuse is around 130 °C, long time ago I replaced mine, 3 days later got thermal fuse blown. Then I replaced again, but not welded it to the terminal, just wrapped tightly around it, then tightened with pliers.

[cpttuna]

I had the same problem with one of my 01's. I bought a new resistor from NAPA and that fixed the problem.

[clawdog60]

Heating cooling supply houses have the thermal limit for less than $2 with tax. If you can find a company to sell you one and you can get them in higher temperature ratings if you want. I raised mine to 154c