Intertherm MAC 2254

[sincewhen]

Hello, I have an Intertherm MAC 2254 which I do not believe is operating correctly. I replaced one limit switch which had burnt off one of it's connections. The furnace now works, but when it is not blowing it makes several popping or clicking noises. Also the furnace itself emits a lot of heat when the blower is not operating (I think from the coils). I have a few questions I hope you could please answer.

Is it normal for coils to heat without the blower engaging?
Are there other parts that should be checked and how do I test them?

Any and all help would be greatly appreciated.

[Robert]

Hi,

Slide the blower housing out after removing screws and disconnecting wiring.

Look down on element coils to see if one has broke or simple fallen and is now touching another coil or the frame.

If so, it will energize the coil and blower won't be on because it bypassed sequencer/blower circuit.

The clicking will be limit shutting down coils due to no blower and overheating.



Thanks,
Robert

[sincewhen]

Thank you for your response. I checked all three coils and they are in good shape. Is there any way to check the two sequencers to see if they are working properly?

Thanks again

[Robert]

Test across the element end terminals for 240vac when you feel it heated up.

If you have 240vac and the t-stat is not calling for heat, then the sequencers are allowing voltage through and are bad.


Thanks,
Robert

[sincewhen]

Just tested elements. The furnace has 3 elements, the top 2 are controlled by one limit switch and sequencer. Those had no voltage
when thermostat was down. The bottom single element also has a
switch and a sequencer to itself. This element did turn on for a short
time then click off while thermostat was down.

Once again thank you for your responses.

[Robert]

Hi,

The oem sequencers are no longer available. There is a universal sequencer that replaces the oem, but it is pricey due to age and hard to find.


Universal Sequencer #L36-658 @ $175.00 + $8.00 shipping.

It can be ordered by calling toll free after 9 AM CST to

1-877-263-7860 and charging to Visa or Mastercard.


You could get a cheaper and newer sequencer, but the timing sequences may not be same or close eneough to operate furnace correctly.



Thanks,
Robert