2001chevy mailbuheater won't work,my heat Gage isn't weather, , but" I can take out two relays and it works , but then the car over heats.why? What is the problems

sounds like might b a main fuse. do u have a kick panel and a box under the hood? sometimes a main relay or fuse will cause many electric things to go out.

natural for engine temp to rise in Traffic - Until Themostat opens ) cooling fan sensor kicks on fan . But Antifreeze is not just a Cold weather item . Coolant is Absolutely Necessary for Hot Days . You must be full to recovery bottle setting of cold when checked prior to start up . Coolant for your make / model is Reddish - Pink colour and should have a reading of -25 thats negative 25 degrees the Lower the Better even - 50 .. Why ?? - 50 is 50 %% antifreeze / Coolant Concentrate MIX Gives Hot weather cooling Ability or very cold weather starting / winter HEAT .

Turning on the heat removes heat from the engine as it blows it on you. Make sure first that there are no air pockets in your cooling system as that can cause high temp reading and malfunctions in proper fan engagement. If that looks good test your fan, if it is working then test the fan relay, if it is working test the temperature sensor that gives the relay the go ahead to engage the fan.

Did you check in the fuse box in thje engine compartment?

could be as simple as your gage isn't working or it could be your oil pump needs to be replaced, if it isnt burnning oil and isnt loosing oil more than likly it's your gage ,if the pump's not working you won't get oil; to the engine and will over heat and could lock up

You definatly have water inside the car. Pull the carpet back in the front and rear checking for water leaks. The only way frost can develope inside a vehicle is the presents of moisture.
The other possibility is your HVAC drain is plugged and water has built up inside the heater motor area. Have the drain checked and cleaned.

Start is usually a momentary circuit. It closes a secondary circuit commonly addressed as the run circuit. Secondary. It sounds like the secondary (run) circuit is stuck closed and the thermostat cannot cancel it out when the temp is reached. The primary circuit is generally low voltage, 15vDC controlled by the t-stat and the secondary high voltage (110v A.C., is engaged on signal from the t-stat. You replaced the stat so that is not an issue. The low voltage controls a rela, Large and small wires are connected to this relay. These relays have or are contacts and they do fail. Either they stick or not work at all. Take caution with this relay because it will also make your hair stand on end if attention isn't given to the 110v side. Food Luck and be safe. -Ned

BY THE WAY, a TOWN CAR WITH AN aTWOOD 10 GALLON WATER HEATER?hMMM.

put a piece of cardboard in front of radiator for some warmth in car ,the needle is a loose or damaged wire worry about that when weather is warmer

them guages do give trouble..id say you need to replace the whole cluster to solve the problem..get one with low milage ina breakers yard ,,way cheaper too

Replace the thermostat, if that does not cure the issue you have a slight head gasket leak. I am a retired Ford dealer tech and this is what I have found causes this issue.