Basement a.c. problem

[simbil]

'05 Winni Adventurer, gas w/basement air. On 50A and park voltage is good.
The basement a.c. won't start in cooling.
Switching it on, the outside blower starts, followed seconds later by the first compressor, shortly after by the second compressor. Good for a few seconds and shuts down.
What doesn't come on is the inside blower, which I understand is supposed to come on first. Tried wiggling the slider switches for dirty contact w/o success.
Any suggestions welcum. It's been in the 90's and no fun.

[bluepill]

Possible that a thermostatic "Safety" cuts out the system to keep the evaporator coil from freezing when the inside blower doesn't run.

Does the blower operate if you turn the thermostat "Fan" switch to "ON" rather than "AUTO"? (IT should).

Does the blower come on after 30 to sixty seconds with the heat on? (It should).

If the blower does not run in any of the above modes, check for power to the furnace (blower) itself.

[Pelledan]

Hi,
On any A/C system if the evaporator blower fails to come on, the refrigerant pressure will drop to the point where it will trip the low pressure safety preventing the evaporator from freezing and the protecting the compressor as well. Depending on the unit, that safety may automatically reset itself once the pressure begins to naturally rise during the 'off' time at which point the system will try and start again. If this process of autostart doesn't happen, then the system is further protected by a lock out relay where once the low pressure switch is activated, it uses that relay to prevent another attempted auto start. The relay can be manually reset by waiting for the pressure to naturally rise during the off cycle, then cycle the systems power off then on (that resets the relay) and try to start the system again. The long and the short of it is that the system is protecting itself because the furnace blower does not work. In the A/C mode that blower is enabled from a fan relay somewhere in the system. I suspect the relay is bad, but here's how you can check. With the A/C and heat off, turn on your blower only if you have that setting available at the thermostat. If no blower, the relay is bad. In the heat mode, the furnace does not use that relay and instead uses a blower fan switch that's enabled by heating time or temperature. However, if THAT does not bring in the blower, then the blower motor itself may be the culprit.
Dan

[DancinCampers]

My manual says possible solutions:

Tstat, Run Capacitor, Wiring, Fan Motor, P.C. Board.

Did you wiggle the slide switch for Hi/Lo Blower Speed?

I think the indoor fan motor capacitor is located near the PC board, along with the compressor capacitors.

[Sammie]

Try moving the slide switch on the thermostat back and forth several times. I recently had similar problems with mine and ordered a new thermostat and after sliding the switch several times it is now working fine. I still haven't installed the new thermostat. I guess now I have a spare thermostat.

Sammie

[sam-tip]

I had a wire come off of the fan motor once. Everything turned on but the inside blower. I opened it up and a wire came off a spade connector in the fan motor area. All I need for tools was a screw driver and a torx screw driver.

Good luck

Doug