Intertherm FEH-015HA fan not starting-A/C

[pnky_14]

Hello,
I have an Intertherm FEH-015HA where the HEAT works perfectly when t-stat set to auto and fan/blower set to auto. However, the A/C will only kick on and stay on when the fan/blower is set to the ON position. I've read multiple posts about the opposite problem where the A/C works and it's the heat that has issues, but have yet to see any posts on this. If anybody could direct me to any forum post regarding this issue or just shed some light on the issue I'd greatly appreciate it. I replaced the t-stat, thought maybe the 1986 model DUOTHERM I had was bad, but same issue with the Honeywell, so now I have to troubleshoot the actual unit. Fuses are all good...just don't know where to go from here. Thanks in advance!
DP

[Robert]

Hi,

1- When you say a/c won't kick on in auto, is it the outside a/c condenser only not coming on or that and the inside furnace blower also ? One or both ?

2- How many wires are connected to the t-stat ? Two or four/five ?


Thanks,
Robert

[pnky_14]

The outside unit kicks on but the inside fan/blower doesn't kick on. I have 4 wires connected to the t-stat. I have yellow to Y, green to G, red to RC, and white to W. Those are the only 4 hooked up. I hooked it up exactly how the other stat was hooked up.

[Robert]

Sounds like either a stuck fan relay or a wiring problem in the cooling circuit.


When the t-stat calls for cooling, 24vac should go through the green t-stat wire to fan relay coil (1 and 3). That should energize the coil, open contacts 5 and 6 and close contacts 2 and 4 sending 120vac to motor for cooling high speed 1 leg.

Other 120vac leg comes from fuse.



Thanks,
Robert

[pnky_14]

I'm going to do some investigating and see what I can come up with. Thanks for the replies!

[Robert]

You're very welcome, happy to help.



Thanks,
Robert