how do you fix a hvac system that does get power from contactor??

Question

if you push contactor in manually it works just fine??

Answer 1

Sounds like a 24 volt control problem, check the transformer at you furnace, check thermostat and wiring. Check for 24 volts at the coils on contactor.

Answer 2

Hmmmmm, If you know to push the contactor to make it run, yet you do not know how to trouble shoot the system, what the hellO are you doing in there to begin with. Any safety switches like low or high pressure cutouts ? Do you have 24v at the contactor coil ? Is the breaker on for the furnace or air handler turned on? Is there 24v at the secondary of the transformer? Is there 24V on the RC terminal of the thermostat? In the cool mode is there 24v on the Y1 terminal ? Is the indoor fan running? Is there 24V on the wires going to the outdoor unit from the furnace or air handler? Is it a heat pump? On the outdoor unit, does the compressor and the fan both run when you push in the contactor ? If you can't find the problem in less than 20 minutes, you do not have any business working on it.

Answer 3

if you push in the contactor it works,
The t-stat inside is what controls that contactor make sure it is in the on position and set to auto.
try and put it in the fan only fan should blow
then put in auto , it might reset it self ( newer ones will)
make sure the filtr is clean
if yo uhave a tester check for power at the t-stat should read 24 v dc
if not outsdie test the transformer AC in and DC out if yo uhave it there , then you do have mice problems they cut their teeth on low voltage