How do you repair a 1999 jeep grand Cherokee heater fan?

Answer 1

You dodn't say if you have automatic climate control or not - I can tell you how to fix the standard heat/ac. Digital/climate control is not the same.

The first thing you need to do is check your fuses. You will find the fuses under the hood and in a plastic box. The inside cover will tell you which fuses go to what.

If the fuses are good - then you have to look at your relays and resistor. BEFORE I buy parts I check to see where the problem is. I do that by working y way back from the fan. I use a small voltage tester - looks like a pen that lights up and has a positive and a negative probe. Test the wiring at the fan, if there is current - take out the fan and attach it directly to the battery. Make sure you have the right wires attached to positive and negative. Hold the fan tight, keep your fingers AWAY from the fan paddles - if the fan works it will really turn fast. If it doesn't work - you need to replace the fan. If it work - put the fan back in and check your relay - I pull the relay and put the probes in the female end of where the relay plugs in. Do this with the Jeep turned on and the fan on. If the fan comes on - then you need to replace that relay. They usually cost less than 20 bucks. If there is current and the fan doesn't come on - then check the resistor - that's up under the glove compartment. You pretty much have to take out the glove compartment door and stand on your head to get it. It will look like a ceramic block attached to a plastic plate. If it's melted or blackened - it probably needs to be replaced. The resistor is what controls how fast your fan turns. So if it goes out - you'll probably experience the fan working on certain speeds - like only on high or low. They usually don't go out all at once. So check the current. Afain with the Jeep on and the fan on. If the fan comes on - the resistor should be replaced. Note: If it comes on you won't be able to change the settings of the fan because you'll be getting full current - it'll be on high. A resistor costs around 60-80 dollars.

If the fan doesn't come on - then it's probably the relay at the fan knob. The bad news - you have to take the panel off and open the box that houses the relay. Worse news - that relay is probably and aeromat relay - it's purpose it to stop the current and then regulate the fan settings. It's also a very difficult relay to find. I have found relays that match that one - but they do not work. You may be able to find the right one at a Radio Shack but I wouldn't hold my breath. To check that relay you pull it out - it looks like a little black plug. Use your probes between the female parts that the plug prongs go in to. Again - Jeep on - Fan on. If your fan works - it's that stupid relay. Even worse news - the dealerships do not carry THAT relay. You will have to buy the entire unit at about 200 bucks.

MY solution - cost me about 10 bucks. I made a jumper between the female receivers where the relay plugs in. Problem - the fan doesn't turn off - even when the Jeep is turned off - keys out of ignition. That relay is fed directly from the battery. Solution - a kill switch. I wired a kill and installed it just under the driver side dash board. No wires hanging out, put everything back together and reinstalled the heat/ac box. When I am in my Jeep - I just turn on the current to my fan. My fan works on all the settings, the heat and ac rock. Just have to turn off the current before I get out of the Jeep so I don't drain my battery.

Those are the major things that are the usual culprits. Unless you've done some recent work under the hood - there probably isn't a problem with your wiring. If you had a problem with it - nothing would have been getting current. If you check all those thing and have no current - then it IS wiring between the battery and the cab. Look for broken wires- frayed wires, bad grounds.

Good luck.