1994 Honda Accord Overheating unless Heater is On.

hi,is the fan cutting in when it should. Is the water temperature sender working correctly

sound like your heater core is leaking

If you have changed the thermostat, could be the water pump needs replacement, especially, if you are overheating still.

Yes clogged heater core may be the answer in your case .

temperature sensor for the auto choke

Hi dakota_love what we need to verify is if your cooling fan is operating properly, what you need to do is first bring temperature close to redline
(but don't hit redline it may cause a blown head gasket) than you need to open up the hood with the engine running (and temperature close to redline)at and see if any of the cooling fan in front of the radiator is coming on, please update once this part of diag. is completed so we know which way to direct for further diagnostic.

There could be an obstruction in the heater core under the dashboard. It's also possible your thermostat is stuck in the open position. I'd start with changing the thermostat. As far as your A/C goes, either you have a slow refrigerant leak and whomever did the servicing didn't bother to check for leaks and/or the A/C compressor could be malfunctioning. Unfortunately A/C problems can be costly.

change your thermostat, yours is sticking open not letting the coolant in the engine to warm up

There are two temp sensors on the engine to the left of the distrubutor. both on the goose neck. I have found that often a false hot occurs when one of these goes bad.

is it the temperature control knob or the fan speed knob? the temperature control knob is hooked to a cable that operates a valve in the engine compartment. sounds like this is your trouble area...you can open the hood and locate the heater control valve near the firewall...have someone turn the knob to see if the valve lever opens/closes. if it does it is bad. if it does not move there is a problem in the dashboard behind the heater control unit.