Heater only stays on for about 15 minutes, thermostat knob seems striped

The flame should probably be controlled by an internal thermostat - we had a heater like that. We could select 2 or 4 burners but there was no way for us to turn them down and the control seemed to have no effect, though 15 or 20 minutes later the flame died down and the control knob began to have an effect.

The system was wholly mechanical - like an old oven.

Turn the gas knob to the pilot setting, press it in and hold it. You should hear gas escaping while in this position. Do not let more than about 10 seconds of gas out at one time as it may pool. Light the pilot while holding the gas knob down for a minute. Release the gas knob (the pilot flame should stay lit) and turn it to the ON position. To make sure the gas heater is working properly, turn up the thermostat and see if the heater heats up. How To Light The Pilot Light On Gas Heater

You need to turn the knob on the gas valve (inside the heater) to the "pilot" position. Then, while holding a flame over the pilot assembly push down on the knob.

Gas should come out of the pilot and ignite. Continue holding the knob down for 10-15 seconds. Release the knob and the pilot should stay lit. If not the pilot generator may need to be replaced.

Turn the knob to the "on" position, close the heater and turn the heater on and turn the thermostat to hot. The heater should fire. If it does not fire and the pilot goes out, that may also indicate a pilot generator problem.

If you know where the heater hoses are, lift the hood after car has warmed up I mean the engine running for at least five minutes, feel the heater hoses, if they are warm or hot and still no heat from the heater, you have an in line proiblem. if hoses remain cold, replace the thermostat with a winter thermostat.

If this is a standing pilot system, turn the gas valve to pilot position. push in the knob & hold while lighting pilot...keeping holding knob down for a minute... this will pick & hold the gas valve. Let go of the knob & see if the pilot stays lit, if it does, then turn the knob to on position & the furnace should start if there is a call for heat from the thermostat

Turn the Gas Control Knob inside the heater compartment from OFF to PILOT. Push in the knob and hold it, at the sametime push the ignitor button (will probably be a Red button). Once the pilot lights, continue to hold the Control Knob down for one minute. Then ease off of it. If the pilot stays lit, turn the Control Knob to the ON position. The burner should light, if the Thermostat is set higher than the ambient temperature in the house. If the Ignitor button doesn't work, you can match light the pilot. Just be careful and follow the instructions above, once it's lit.

Hope this helps solve your problem.

Sounds like a sticking/stuck thermostat.
Does your truck have cooling fans? If so, they should NOT be running when cold. If they are, you have a bad thermo sensor. If you have a temperature guage, what is it doing when you go from cold to hot to cold again?

If you see frost behind the back wall or begin to notice the fresh food compartment getting warmer then you might have a defrost problem. The defrost system is a heater and termination thermostat inside the evaporator and A timer. The termination thermostat shuts down the heater when it gets to be warm enough for the frost to melt. It is important for the thermostat to kill the heater because the defrost mode is 21 minutes long.
If that heater was to stay on for 21 minutes the ice box would be severely damaged. The Timer might be hung in the run mode and not jumping into defrost every 8 or 10 hour as it should. The heater element might have gone bad or the termination thermostat might be swollen and failed. That is some ideas to check. Service manual


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Have the Hayward guys come out and prove to you that it is indeed low pressure and then get an estimate for repair costs. Assuming there is no warranty in effect, you might want to locate the heater manufacturer for guidance. They may have a website that may be of help.

Hi,
Yes it would seem that the thermostat or the knob would be the problem...when checking for voltage you need to check for 220v across the two terminals for the heating element. You will have 120 feeding back and forth all over the place but the fan and element will only work if they have 220... so you can have voltage and it still not work...

heatman101