Try taking the car in for a rad flush. You may have a restriction. Check also that the hoses are not kinked, block heater and rad.
The rear air conditioner unit has a thermostat that is malfunctioning and needs replaced.
thermostat setting /very low gas pressure or compressor not working.
If a thermostat is not working properly, you cannot calibrate it. It must be replaced.
I replaced my thermostat recently. Try Askarepairtech.com. They have lots of them and they have good pricing. Give them a look.
because the water pump is not working properly....
sounds like the heater core is out or you have an air bubble in the cooling system
1. Low on freon.. 2. Electrical issues.. 3. Bad inside thermostat.. 4. Bad outside capacitors..
MY CAR WAS DOING THE SAME THING NO HOT AIR COMING OUT OF THE HEATER I CHANGED THE THERMOSTAT. IT WASNT THE THERMOSTAT. I GOT TO CHECKING AND THE SEAL IN THE WATER PUMP WAS BAD. I REPLACED THE WATER PUMP AND IT WORKS FINE NOW.
I have a 2000 zx2 and it has a thermostat, if that is your question. Having said that, my heater quit working and it turned out to be the cable came loose under the dash on the left side of the radio. At first I thought it was the thermostat but was wrong. Duct taped the cable in place and the control and heater started working fine again.
If the engine is taking a long time to warm up or the gauge registers low heat the thermostat probably is stuck open and needs to be replaced. If the engine runs hot check the temperature of the upper radiator hose. If it's not hot the thermostat is stuck closed and should be replaced. If the upper hose is hot it means the thermostat is open and working. Cooling problem could be restricted radiator.
Have you checked for leaks? also the cooling fan may not be working.
If you have an old ISUZU Trooper, the radiator thermostat may be not working. Therefore, it will not let cool water from the radiator into the hot engine, even if the radiator is full. Have the thermostat checked and replaced, if necessary. Good Luck