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johnstahl · Nov 20, 2008, 10:11 PM

I have a heater problem where the heater seems to start and run through a cycle and shuts down at the end of the cycle. When it shuts down it shuts down the thermostat as well.

I first thought the switch on the front panel was bad because the first time this happened I removed the cover looked around and put the covers back and it started. It then stopped after the first cycle. I remover the covers again and taped the switch down and it seemed to work again. (I thought it worked for a couple cycles but not real sure about that) It failed again.

I have had the HSI fail and this is not the case here.

Any ideas?

hvac1000 · Nov 20, 2008, 11:10 PM

Shuts down the thermostat?

This is a strange one.

Brand of equipment?
Exact model number of equipment?
Brand of thermostat.
Exact model number of thermostat?

Have you made any changes to the thermostat or your system in the past year like replacing with a new thermostat ETC.

johnstahl · Nov 20, 2008, 11:18 PM

The furnace is a Carrier WeatherMaker 8000 the thermostat is a carrier programmable thermostat. Both have been there since install several years ago.

hvac1000 · Nov 21, 2008, 01:32 AM

I would suspect the door switch first. Temporary eliminate it from the circuit. Do not tape it just bypass it.

If that does not work

I would try to bypass the thermostat.

I believe R=Red and W=White are the wires that activate the heat section.
Disconnect those wires at the furnace then with a jumper wire or aligator clips jump the R and W terminal. This will cause the fiurnace to activate. After 1 or 2 minutes disconnect. Then jumper the W and R again and see if it starts without fliping the main on off switch or playing with the door switch. (DO NOT turn the power switch off and on for this test you will voild the test because every time you do that you reset the furnace control)

Cycle this way a few times. If the furnace relites without having to play with the on off switch then you know it is the thermostat.

This is a simple by pass test. Post back with the results.

johnstahl · Nov 21, 2008, 08:37 AM

OK well I think the issue is with the source power. I went to do the test you suggested and there is no power at all.

The power comes from a switch. I pulled the switch out and checked the volts. I was only able to get 20-24 volts on the line. Does this sound like a circuit breaker. I flipped the circuit breaker and it did not do anything.

How do I test the circuit breaker?

johnstahl · Nov 21, 2008, 08:49 AM

I tested the circuit breaker and it has 124v coming out. I assume this is correct.

So now why would the power at the switch show only 20-24 volts?

letmetellu · Nov 21, 2008, 10:06 AM

Quote: I have a heater problem where the heater seems to start and run through a cycle and shuts down at the end of the cycle. When it shuts down it shuts down the thermostat as well.

What do you mean that when the heater runs through a cycle it shuts down the thermostat as well.

Is your thermostat battery powered? If so I would change the battery/s.

I am not sure what switch you are checkiing that you get 24 volts, but that is the amount of voltage that you are suppose to get on the low voltage side. So explain the switch please.

Whad do you do to make the furnace start a new cycle?

johnstahl · Nov 21, 2008, 02:24 PM

HVAC1000,

OK I know it is an electrical problem. I ran a short extension cord (heavyduty) from a working plug to the junction box of the switch and connected the furnace to that power source the furnace worked fine, and has ever since.

At the circuit breaker the power is 127 volts at the end of the wire at the switch it starts at let say 10 volts and drops to below 1 volt then hovers around 0.4 volts. What would cause this to happen? Does the power go somewhere else before the furnace? I do have central air as well, but it has another circuit for that. I ultimately shut off the circuit breaker to the furnace until I know what is going on.

Any help is great.

Thanks

hvac1000 · Nov 21, 2008, 02:50 PM

I have no idea where the power goes in your home but I do no that the furnace needed power to work and now the furnace is working. All you can do is track down the bad circuit or abandon the old bad one and run a new circuit wire from the electric panel the furnace. That will fix the problem.