I have a couple questions about cold weather features on my 04 4.2L

1) Seat heaters/warmers. How warm are they supposed to get? I tried the driver side one a couple times but never really noticed it get warm. I'm assuming its working because the indicator lights came on when I pressed the button. Other cars I have had, if the seat heat wasn't working, the light on the button didn't glow.

2) Heated outside mirrors. I didn't know that the car had any, since there is no little symbol on the glass, the rectangle with wavy lines going up. In any case, I found that they are tied to the rear window defroster. When I used it, the rear defroster seemed kind of weak in clearing the back window. The right side mirror warmed and defrosted nicely, but the left side didn't. I thought it might be a fuse but found only 2 in the handbook, one for the window and mirrors together and a second for just the window.

Is this normal behavior, or is something wrong? (obvious the left side mirror is a "wrong")

Thank you for any comments.

 

Turn the heaters on and feel with your hand as they warm up...within 90 seconds they should be noticeably warm...the mirrors should be warm all areas of the glass...sometimes one pf the filaments will fail and only spot heat

 

Seat heaters:

Have you tried the passenger side for comparison?

Wiring diagrams are here, section 11.6:

http://www.jagrepair.com/images/Auto...x2062004en.pdf


If the passenger side seems okay, access the two seat heater modules and remove the plugs. From there, you can read through the heating elements and the temp sensors. Note how each seat has two heating elements in series. Leave both seats switched off for a while so the temperatures are similar. You don't want to be comparing one seat hot and the other cold. The resistance through the pair of heating elements should be similar side to side. If one side reads open (no continuity), you've got a bad element or a broken wire.

Compare the temp sensors in the same manner. At the same temperature, both temp sensors should show the same resistance value. Could be the heating elements are fine, but an inaccurate temp sensor on the driver's side tricks the controller into thinking that seat is already plenty hot, and thus shuts off the heat.

Another option: Have you considered a portable seat heater instead of a built-in system? I keep a portable system with me at all times, primed and ready to go. Works anywhere I need it, be it my car, public transportation, an airplane, etc. Only works on the bottom seat cushion, though, not the back. Unfortunately, sometimes it smells like sulfur, and does tend to leave a film on one's teeth.


Rear window/mirror heaters:

See section 10.2 in the same wiring diagram. Note how all three heaters are controlled by relay R1 in the trunk. Might be worth popping that out and removing the cover for a looksee. If you find evidence of arcing, that would cause low voltage to all three places. A new relay may restore proper operation to the rear glass heating grid. If the element is a little weak on the driver's side mirror, a proper voltage supply may restore proper operation there, too. To test the relay, you can swap it with another location from a circuit you know is operating properly.