Expert: Skip Bollinger - 1/9/2010

Question
Hi i have a 1999 Saab 9-5 and the heater stop working.. I'm not sure if its the blower motor or the relay/electrical. How would i check this myself? I'm willing to fix it myself i just need to know how to figure out which one it is (Blower Motor or Relay/Electrical)and where its located in the car, i thought it was under the glove box but i am wrong.. please help me "It's freezing without heat!!!"

Answer
David,
  I'm about as dumb as a person can get when it comes to repair. As noted in my Profile, I'm a Parts Specialist, NOT a Tech but will offer these thoughts for your consideration. Here we go..
  Please allow me to preclude this answer with this statement. You have an 11 year old car. While very uncommon with the wiring used in vehicles today, your problem could be a broken wire.
  First of all, I'd check the fuse. It should have one. Make sure it isn't blown. IF it is good,
  Find the plug that goes to the blower motor. Run a "jumper wire" from the positive side of the battery (marked +) to the wire that goes to the blower motor. IF the blower motor has a 2 wire plug, it grounds through the wiring harness and not the chassis of the vehicle. You will need to run a jumper from the other terminal (IF it has 2) to the chassis for a ground. Make sure they DO NOT TOUCH. You don't need to worry about which is positive and negative. IF you have them hooked up backwards, the motor will just run in reverse rotation. Does the motor run? IF NOT, the motor is bad. IF it does run...
  Pull out the Blower Resistor. It should be located in the case adjacent to the blower motor. Does it look like it has been hot and melted? IF so, replace it. IF not...
  Get a Test Light and find the relay. I have no idea where it is but most Public Libraries have a "Reference Section" and in that section they have an Automotive Section. You should be able to find a Repair Manual that covers your car and be able to find the location if the Relay or just call your local Saab dealer and ask them where the Relay is located. When you find the Relay, unplug it and look at it to see if there are any obvious burns or signs of overheating.
  IF there are signs of burns, the Relay is probably bad. Have your local parts store order one in. Take your old Relay into the store along with an OHM Meter. Compare the readings from the OHM Meter between your old Relay and the store's Relay. IF they are the same.. Go to the next step.
  NOW, with the key ON, check the wires coming to the Relay to see if any have current running to them. Make sure you have the blower switch on the dash turned ON. If you do have power to the Relay, I'd consider the Relay to be the problem, no matter what the OHM Meter test said. It is VERY EASY to test Relays incorrectly unless you are experienced in such tests. IF you DON'T have power to the Relay wire, I'd suspect the Switch.
  Unplug the harness going to the back of the Switch and using the Test Light, see if you have power there. Make sure the key is ON. If you do, the Switch is bad. IF you don't, you have a wiring problem.
  Back to my initial statement of a bad wire. While doubtful, the wires can be checked with the key OFF, with the OHM Meter.
   David, I know this sounds complicated but welcome to the world of Auto Repair. Electrical paoblems can be a nightmare!!
   I don't know where  you are in the country but it is supposed to be -10 here this weekend with windchill of -30 to -35!! I hope you have a heated garage. Good luck. I hope this helped a bit..
Skip