Heater not working

[Matt Johnson]

Fan works, but the heater's not making hot air. (Thank God I live in Cali).

Anyone got an idea of what the usual fix is and how much it might cost?

Don't want to let the dealer do it if it can be avoided.

[Zack]

Try burping the cooling system first.

[Egon Spengler]

How do you burp the cooling system... I have the same problem and went to work in the frigid New England weather with very little heat

[jgc61sr2002]

There is a bleeder on the horozontal cooling line above the radiator.

[fastblackmerc]

There is always the search function. Burping the cooling system has been discussed a number of times.

[Merc-O-matic]

You might need a new thermostat......cheap fix.

[Vortech347]

No need to fear the issue is easy to fix... I just fixed it on my car.

Symptom. no heat, even when the car idles for a while and while driving it in cold mode, aka no more then 2000rpm. But when it warms up you floor it or goose it and you've got heat!!

The core is one of the highest points in the MM system, air gets trapped there very easy....

Step 1. Pull the front of your marauder up on either ramps or even a few 2x4's to get the front slightly elevated. After shooting the ramps across the garage because of a dirty/salty/winter sealed floor use a few 2x4's to lift the front.

Step 2. Use a 3/8th ratchet with 1/4" adaptor. (USE THE ACTUAL RATCHET WITH A BREAKER BAR!!, No ADAPTORS!) This baby fits TIGHT. See step 3 as to why.

Step 3. Use Channel Locks on the fitting after breaking 1/4" adaptor inside the fitting hole. Amazingly it didn't slip at all and grabbed the outside and backed it out

Step 4. Swear a little bit while having the fitting in a vice and digging said 1/4" adaptor part out.

Step 5. Go top off the coolant where the fitting was. DO NOT replace the top at this time.

Step 6. Back to the work bench. Break small snap-on and craftsman screw drivers while trying to pry said broken adaptor piece out.

Step 7. After having a beer, cool down session, and watering the tree behind the garage. Go top off the coolant again, you'll notice it will go down.

Step 8. Back to the bench with hells fury. Turn the fitting upside down and smack it on the bench. Snap-on, and Craftsmen screw drivers tips and adaptor part fall out.

Step 9. Top it off one more time then go to bed. Leave the cap off still and front elevated.

Step 10. Go out in the morning and top it off again. While installing the fitting back on don't forget to smear some coolant onto your nice white work docker pants, a must when you're late.

As soon as the temp gauge started to move I HAD HEAT!!!!!!!! :banana::banana::banana:


I added a total of 1/4 gallon!!!! The trick is to pour slow, and like I said let it take time to burp!!! Also I strongly recommend water weter because it will make the coolant more "fluid" and have less surface tension to trap air bubbles.

Hope this helps!!

[Go Mifuni]

There is a bleeder on the horozontal cooling line above the radiator.

What he said. :up:
Mine did the same thing two years ago and has been fine since. The cross-over pipe is the highest point in the system. Remove the plug and fill from here instead of the reservoir and you're good to go. If this doesn't do the trick, only then I would start looking into things like the stat.

[Egon Spengler]

thank you... sorry for not looking at other posts... I work alot and dont have time to search threads

[Matt Johnson]

No need to fear the issue is easy to fix... I just fixed it on my car.

Symptom. no heat, even when the car idles for a while and while driving it in cold mode, aka no more then 2000rpm. But when it warms up you floor it or goose it and you've got heat!!

I have no heat at all. Period. Not at high rpms or after the motor is warm.

Do you still recommend this fix?

[jgc61sr2002]

If you bled the system and still have no heat I would change the thermostat.

[Go Mifuni]

If you bled the system and still have no heat I would change the thermostat.

Before digging into the t-stat, find out if your blower is working. When you move the speed control wheel up to max, can you hear a rush of air?

[Matt Johnson]

Blower's working fine. I haven't bled the system yet, haven't touched it.