Ask the Expert

Let Zimmer Heating & Cooling help you find the answer.

Have any questions related to your HVAC systems?

Let Zimmer Heating & Cooling help you find the answer. Simply post your questions below, and one of our HVAC experts will help you reach the optimal comfort in your home.

If you are having trouble or experiencing an HVAC emergency, please call our after hours service for immediate assistance.

I have a Tempstar 7000 furnace. I think the fan limit switch may be bad. I couldn’t seem to get it stay fired and running. Eventually the furnace just went into a mode where the blower will run constantly but now it won’t ever ignite. Even after I turn the power off to the furnace, as soon as I turn it back on, the blower begins to run. I wonder if there is a way to reset it?

Limit issues are usually caused by the following.
Dirty air filters, clogged evaporator coils or closed registers. Limits only trip a few time before failing. I recommend have a service tech evaluate.

We have a Carrier Performance 96 2-stage gas furnace and an older Carrier Performance Series electric Heat Pump configured in a dual-fuel configuration using a newer Performance series Edge thermostat. Because the gas furnace is our only gas appliance, I have our gas shut off each year in May under the assumption that any minor remaining cold spell could be handled by the heat pump operating independently of the gas furnace. I’ve tested that theory today and it doesn’t seem to work that way. The gas is shut-off. I’ve turned the thermostat on “Heat” and the house temperature is low enough for the heat to kick on. The blower starts and runs for about 2 minutes then it stops. The furnace flashes a “34” on the status light indicating “Ignition Proving Failure”. Can I configure the thermostat or do something to force the heat pump to run without the furnace itself trying to run? The furnace can run w/o the heat pump, why can’t the heat pump run with just the blower and no furnace?

In the thermostat there is a setting to make the heat pump work longer. Need to lower the lock out temperature bringing the furnace on at a very low 25 degrees. This will make the heat pump do all the work.

I have a Lennox 5000 Comfort series l5711u thermostat. When running the air conditioner I will have the temperature set at 68 degrees. My AC will run and run and it will state on the thermostat that the current temperature is 68° but I know my house is colder than that. I will switch it over to heat mode and the heat will kick on and run for a while until the house heats up to 68 degrees. Why is my system not shutting off when it hits the correct temperature?

It appears the thermostat has failed to disengage the cooling signal. It appears the thermostat needs replacing.

Does anyone know how to convert a 10 year old infinity system furnace with a heat pump to by pass the solid state control board and just use a conventional t-state and conventional wiring to contacts.

The cost would out weigh bypassing the controls with a standard thermostat. The system will not function properly without the required controls.
There has been an upgrade in the thermostat control to enhance the functionality of the system. Feel free to contact us for further questions.

It doesn’t appear that my blower is working in my furnace. The AC is pumping cool air into the box but it is not pushed to the rest of the house. The AC hose was dripping water from the condensation before I turned of the AC. I tried the self-test for the blower but it doesn’t work. Is there anything else I can do to try to get the blower working? 

Thanks for any insight you can give me!

There appears to be 2 possible options. First the blower motor has failed, or the relay to turn the blower has failed. A slight possibility is the thermostat is not sending the signal to turn the blower on. Either way, a service call is in order.

Do you service replace units that are part of a dual system. My house has radiant heat and I have 2 a/c units one of which has a freon leak. If it cant be repaired and I have to replace it do I need to replace both units?

The system in question would only replacing. If the other system is working; there would be no need to replace at this time. We can give guidance on the second system when evaluating the one in question.

We have a Carrier Infinity system for our heat pump. The zone button on the thermostat no longer works. Is there a non Infinity thermostat that we can replace it with? The cost of the Carrier thermostat is ridiculous.

The Infinity Zone thermostat must be replaced with another Infinity thermostat. The cost to convert the whole system would astronomical.
I’m looking at purchasing an older home that currently uses boiler heat. I am wondering what total costs I can expect to get a new HVAC system installed? I have no idea what the duct work currently looks like. The home is a 2,000 square foot ranch.
To even start on what is needed for a new HVAC system is to have a visit to the home. The information to start a budget process would require that we look at the home to see what type of system is usable. Please contact our company for further information and thank you for the excellent question.


  1. Check air filters/Replace filters.
  2. Tighten electrical connections.
  3. Clean blower assembly.
  4. Check gas valve.
  5. Inspect flue pipe and draft diverter.
  6. Check operation of safety controls.
  7. Clean and adjust burners.
  8. Test and adjust gas pressure.
  9. Clean interior of burner compartment.
  10. Inspect heat exchanger.
  11. Test for gas leaks in furnace.
  12. Check furnace in operation.
  13. Check CO level.
  14. Check ignition controls.


  1. Check air filters/Replace filters.
  2. Tighten electrical connections.
  3. Clean/check blower assembly.
  4. Check operation of safety controls.
  5. Inspect contractor contacts.
  6. Clean and check condenser coil.
  7. Check and record start and run amps.
  8. Flush condensate drain lines.
  9. Check start‐run capacitor.


  1. Check air filters/Replace filters.
  2. Check reversing valve.
  3. Clean blower assembly.
  4. Check defrost cycle.
  5. Check sequencer.
  6. Check heating elements.


  1. Replace oil nozzle.
  2. Replace oil filter.
  3. Check air filters/Replace filters.
  4. Check ignition controls.
  5. Adjust barometric/draft regulator.
  6. Clean and check fill valve (for boilers).
  7. Drain expansion tank (for boilers).
  8. *Doesn’t include draining, refilling, or bleeding of boilers.
  9. Inspect heat exchanger.
  10. Check fill valve.
  11. Check circulation pumps.


  1. Clean housing.
  2. Clean drain.
  3. Replace water pad.
  4. Check operation.


  1. Remove and clean cells.
  2. Check or replace filter
  3. Check power pack.
  4. Check operation.

If you are interested in our Residential Maintenance Program, with discounts on the above pricing, please contact us and one of our customer service agents will get back with you as soon as possible.