I have a new goodman 5 ton heat pump with a programmable robertshaw t-stat. It works great in a/c and elec heat. The heat pump will work fine for the frist cycle. When it does the second cycle it starts OK, but when the compressor starts the blower in the house will slow down. It does it for about 30 seconds, the compressor will stop and the blower will pick up. It will run for a few minute and do it all over again.

Is the heatpump wired to its own breaker? I hope the airhandler and heatpump arn`t on same circuit,, the heatpump starting shouldn`t be pulling down the airhandler blower,, if I`m understanding right

is the heatpump wired to its own breaker?,I hope the airhandler and heatpump arn`t on same circuit,,,,,,the heatpump starting shouldn`t be pulling down the airhandler blower,,,if I`m understanding rightGood call. Something is dragging down the power supply to the indoor unit. The outdoor unit may be struggling to re-start due to insufficient voltage or short off-cycle. Check for start-assist accessories at outdoor unit.

Heat pump and airhandler are on separate breakers.

Heat pump and airhandler are on separate breakers.

If you have a voltmeter, check for voltage decrease at indoor unit when blower slows.

When this is going on do your house lights dim as well?

Not enough amps available. A hard start kit will help the situation but it is not a cure for a to small service problem.