Heating, Air Conditioning, Fridge, HVAC/Electric Furnace


QUESTION: Hello Jim,

I'm helping a friend with a furnace problem.
He has a heat pump outside, and a electric furnace for colder temps when heat pump is off. I've checked elements, limit switches, connections, fan runs but no heat from elements (3).  I noticed some water had dripped from the above evaporator over the summer and has rusted a couple of diodes  in the circuit board at the bottom.  Other than that, I'm stumped! Maybe a relay? how do you test for that?

ANSWER: Hello Dustin, I can better help you if you can get me the Make and model # on the furnace. I have serviced hundreds of electric furnaces so I can give some general info:

The elements will come when the temp in the house is 2* below the thermostat setting, when the heat pump goes into defrost mode, or when the heat pump runs for say 15 minute. If the stat has a emergency switch, have him switch it and see if the elements come on.

Let me know. JIM

---------- FOLLOW-UP ----------

York Model # AHP60D3XH21B
       Serial  #ADK8243969
Furnace Model # THGD60S21S1A
         Serial #  WDK8345759

We tried both settings on the thermostat. No change

Thanks again for your help on this


Hi Dustin, I found the wiring diagram for the furnace. There are 2 sequencers ( relays ) that bring the heating elements on.  With the stat calling for electric heat, you need to check the voltage from the stat. There is a terminal strip in the furnace. Put you meter on # 4 and #5 you should have 24v. Then test #4 and #6. This will tell you if the stat is working correctly

Also there are 3 fusible links one for each element. It's not likely all three have opened but it worth checking out.

Let me know what you find. JIM  

Heating, Air Conditioning, Fridge, HVAC

All Answers

Answers by Expert:

Ask Experts


Jim S.


I can answer questions on gas or electric furnaces, ac units and heat pumps. I don't work on boilers,chillers,or home appliances.


I have been in the HVAC trade for over 35 years. For the past 15 years I have owned my own business. I am semi-retired so I can answer questions in a timely manner.

I attended trade school for 5 years on weekends and evenings. This was very hard to do, but well worth it!

©2017 About.com. All rights reserved.