rbarwic1

I have searched and searched on this issue, and have found a lot...however, nothing (that i can find) really covers my issue.

I was out driving around with the family yesterday and had the A/C on fan speed 2. During acceleration sometimes I noticed the fan would stop and then come back on (over past 6 months or so). Anyway, yesterday the fan went off and didnt come back on. I lost fan speeds 1-3, and only the 4th speed (highest) worked.

I jumped on the forums and read a bunch about the AC Blower Motor Resistors and thought I would take a shot - its only a $9 part now, so what the heck? Anyway, at first the fan speeds came back on (all 1-4) then I smelled really strong burning so I turned the jeep off. I noticed the check engine light had popped on too.

I called a buddy who has a rubicon - but still has the 4.0L engine and asked him and we pulled the CEL code...It said P0420 - catalyst system efficiency below threshold - bank 1. We cleared the code and it hasnt come back on, yet.

However, we turned the A/C back on and played with the fan speeds and got the burnt smell out. We then lost fan speed 2 for a few minutes then it came back on and I drove back home. This morning I got back in and once again only the 4th speed (highest) works again.

When I compared the new resistor to the old one originally I didnt notice any burnt/melted looking marks - the old one actually looked in better shape than the new one i had. The new one is probably toast now, though.

Does anyone have any recommendations on where to look/try next? I dont want to keep popping in resistors if its just going to keep melting them.

Any and all comments are helpful...thanks guys!

Firestorm500

You've got a serious wiring problem somewhere. Probably a short to ground somewhere in the fan circuit. The new resistor was not the same (better) quality as the OEM one, which is why it shows more damage.

I would not drive the Jeep anymore, even with the fan "off" until the problem is definitely found and fixed. You could quite possibly end up with a dash or under hood fire and burn it to the ground. Possibly with bodily injury or loss of life.

If you can't figure this out yourself pretty quickly, I would suggest taking it to someone that can.

The P0420 code is not related. You probably will end up eventually replacing the converter to keep that code off, if it reoccurs.

rbarwic1

Firestorm - I have never had an issue before...you dont think it could have just been a bad resistor?

CCKen

Your blower may be drawing too many amps and is melting the thermal fuse in the resistor block.


Pic of thermal fuse. It melts at 262*F.

rbarwic1

The resistor on the bottom of the picture is the old one. The other is the new one - neither look like they are melted or burnt...?

CCKen

The fuse melts internally.


That aside, what year is your Jeep?


You may want to pull the climate control panel out and inspect connector C1 for signs of overheating. Sniff check it too.


C1 is the connector in the pic on your left.





How did the connector on the resistor block look? Did it look like toast?

CCKen

Video:


http://www.bing.com/videos/search?q=...69353C25FE0E61

rbarwic1

Its a 96 Cherokee XJ. I will take the switches off on the dash and take pictures of what I find. The link you sent showed how to check the thermal fuse in a blower resistor - I dont see any burning on the resistor...though i havent tried to turn it on with the resistor hanging out like that.

I will get a pic of the plug too..

Will post what I find shortly.

rbarwic1

Wow - this definitely could have been bad. How should I proceed? Assume I need to get a new switch for the AC control and then a new plug?

Firestorm500

You said in post #1: "I was out driving around with the family yesterday and had the A/C on fan speed 2. During acceleration sometimes I noticed the fan would stop and then come back on (over past 6 months or so)."

rbarwic1

My understanding is that as the blower motor gets older that it requires more amps to function properly. As a result pieces fail as a symptom of this and melt - talked with a few mechanics and they said this is very common on XJ's.

All that being said, I plan on replacing the blower motor to stop the problem, the blower switch as its melted, and the blower switch plug as its melted. I will probably throw another blower motor resistor on to be sure.

Any other recommendations to get this problem behind me?

Thanks for all your help guys!!

CentralPAXJ

I just did this on my 96 when I got it a few months ago. I replaced the blower, resistor, switch, and plug ( I couldn't source a new plug anywhere so I used insulated terminals ). Works like a charm now.

rbarwic1

Ok so I replaced the blower motor, the switch on the back of the fan speed ****, and cut off the plug and used insulated terminals. I did not replace the resistor because I just replaced that the other day and thought it might not be bad. All finished and started it up and everything worked with no burning smell except I still don't have fan speeds 1,2,or 3. I don't know where else to look? I am going to run by and get a new resistor tomorrow just in case the fuse melted internally with last times burning smell?

Thoughts??

Firestorm500

Get another resistor. That's what controls all the fan speeds but high AFAIK.

rbarwic1

Thanks Firestorm - if this doesn't work I'm just going to take her to the shop. I'll report what I find..