Rear window defroster

Heater problem
2001 Chevy Impala 6 cyl Front Wheel Drive Automatic 71000 miles

My rear defrost has stopped working. Any idea what could be wrong? The light on the dash says it's on but the window doesn't get warm.

Electrical problem
2004 Chevy Impala 6 cyl Front Wheel Drive Automatic 42000 miles

Rear window defoster does not work.
Light comes on when button pushed. No noise at relay. Have power to relay on upper right terminal. Left upper right terminal when engine is started.
Right lower terminal changes in resistance when activating defrost switch. No change in left lower.
Relay has been replaced and breaker was changed out with power seat breaker with no change. No power to grid on rear window when switch activated.

I mentioned in my email that I already have the diagram. Your diagram is unreadable an is too small to see detail because it is blurry. I was hoping that you could give me some pointers based on what I have check. The antena module does not affect reception as other people have mentioned. If I have power to the relay (and it has been replaced) then why doesn't it click when the button is activated?

Do you need special equipment to check the body control module? I mentioned earlier that their is pwr to both top pins on the relay. Left side is for the coil so that tells me there is power. Does the body control module act as a ground to complete the circuit?

I think it is the HVAC control module because a jumped the circuit across from the always hot to the rear window and it worked. Athough I would not recommend a paper clip because it get red hot. The relay is misleading because it is not set up the same a the diagram. It is in an X pattern. I will take it from here.

Rear window defroster does not work even with button on (light lit up ) on 2002 chevy impala with small v-6 and 122 thousand miles

My rear defroster is no longer working. It barely worked for a while after I bought it in Jul 2006 (used). Now it's stopped working completely. I did have the battery replaced and it's possible that's when the defrost stopped completely, but I can't positively correlate the two items. I've also replaced the Rear Window Defroster Relay (passenger side fuse box) and that didn't solve my problem. I've checked grid continuity and I get 0 ohm reading (no breaks in the grid). I get 0 Volts across the connectors when the switch is on. The indicator light is illuminated when the switch is on as well. What should I check next? Thanks.

Heater problem
2003 Chevy Impala 6 cyl Front Wheel Drive Automatic 89800 miles

What causes this fan motor to act like this: Sometimes when I start the car the fan runs normally. However the next time I start the car the fan will not run at all and the cruise light is on in the dash (even though the cruise is not on). Also the rear window defogger malfunctions. Then If I put the fan control to the highest setting the cruise light will go off but no matter what setting the fan control is set at, usually around 15 minutes driving time, the cruise light goes off and the fan motor turns on all by itself and everything starts working fine again. The wife thinks the car is Haunted! I said nonsense, lets ask someone who knows something.

Hey dennyp thank you for your response. Is this some- thing I can do at home or strictly a dealer repair. Since the key is on the dash of this model I know it can be very difficult to get behind the dashboard. I imagine that's were the assembly is. Is it possible for a pretty handy "home mechanic"with plenty of tools?

Fan motor and rear window defrost don't come on all the time mechanic says it needs a ac heater control head which is 475.00 could it be anything cheaper

Where is the rear defogger switch to turn on and off on my 2008 Impala