I’ve got a Carrier Performance boost 80 that is not cooling. When I had an HVAC tech come out he said it was an issue with the Equipment Interface Module (box that sits in between the thermostat and control board on the HVAC), he said it wasn’t sending the voltage back to the control board on the HVAC unit when I turned the AC on (the thermostat just always said Wait). He recommended I replace it. So I replaced it but now the unit won’t stay on cool.
1. I set thermostat to cool
2. Wait displays on thermostat for about a minute then disappears for about 20 seconds.
3. Cool On will display for about 15 seconds (nothing is happening though, no fan turns on).
4. Thermostat then says Wait for its predetermined safety time
5. Cool On will display for 15 seconds, then turn off
This cycle continues.
The fan will turn on if I set it to continuously run. I have a constant light in the unit which means it’s getting 24v AC power.
I just noticed my EIMs are different even though they both say THM5421C. Original one is on the right (not connected). I hear it click when it turns on the cool and there is a light on it, but it clicks again then the light goes out.
1. I set thermostat to cool
2. Wait displays on thermostat for about a minute then disappears for about 20 seconds.
3. Cool On will display for about 15 seconds (nothing is happening though, no fan turns on).
4. Thermostat then says Wait for its predetermined safety time
5. Cool On will display for 15 seconds, then turn off
This cycle continues.
The fan will turn on if I set it to continuously run. I have a constant light in the unit which means it’s getting 24v AC power.
I just noticed my EIMs are different even though they both say THM5421C. Original one is on the right (not connected). I hear it click when it turns on the cool and there is a light on it, but it clicks again then the light goes out.
