We have 2 Lennox units one for each floor. Recently 1st floor unit ac was not cooling so we had a guy check it out. he said he pumped 410-a refrigerant in it. AC was back on fine but after two days no AC. I noticed that the fan and compressor are both not running now. Thermostat setting was set to Cool, Fan auto mode. I do get room temperature air from the vents so the inside unit is blowing air. To troubleshoot, I tested the capacitor it is showing 45 and 9.8 for herm and fan points. Next I noticed the relay/contactor the magnet switch is not going in? If i press it down then compressor starts but the fan wont start. So I am stuck here not sure what to do next? I am a DIY guy so any help is appreciated.

Is the fan bad or relay contactor? or some thing else?

thanks
an

 

Does this unit have pressure switches?
If the guy charged the unit, where did he find the leak at?

 

I am not sure if they have pressure switches or not. Where to find them?

The AC guy did not give much info. All he was telling was we need to replace coil.

Below are the models for the outside unit and attic unit. 14ACX-042-230-01 (outside) CH33-50/60C-2F-2 (attic)

the units are 11 years old

 

I show a high pressure switch in the unit literature. Could be a low pressure switch as well that list didn’t show.
Are you getting a call for the unit to run? Check with your meter.

 

Usually when there is a high pressure switch.... there is a low pressure switch but it's shown as optional on the circuit diagram. Can't believe they'd make the low pressure switch an option.

 

Yes there is high pressure and low pressure switch as per the installation manual. I am looking at circuit diagram. I dont see them in the panel when Capacitor and Contactor are located.

Do I need to open the fan panel fro top to see if it is inside unit?


Are you getting a call for the unit to run? Check with your meter.
-- how to check this using meter? I see the contactor is getting 240v from the disconnect.

 

If it’s got both pressure switches they will be in the compressor compartment. See if they are open or closed.
Very likely your out of refrigerant.

 

The quick and easy way to check is to locate where the house thermostat wiring connects to the condenser with wire nuts. If you have 24v there...... good chance the low pressure switch is open.

 

Will do this in the morning.

 

Ok. I am getting about 27v on the condenser. So I opened the panel and located red switch. I pressed it down and the condenser started but the fan won't turn on. Is fan bad? I removed the fuse from disconnect and set the thermostat to off position for now.

I understand the system is out of refrigerant.

 

That was the high pressure switch you reset. That would not be a low refrigerant issue. Hi pressure is caused by no cooling at the condenser. The fan not running causes that problem.

 

Allowing the unit to cool for several hours..... turn it back on and try spinning the fan with a stick to see if it starts. If not.... more than likely the motor is bad.

 

It it okay to keep compressor running with out fan for few hours?

I started to look for motors mine is 1/4 hp with 825 RPM 1.7A

Below in HD has same specs except RPM is 1075. Will this work?

https://www.homedepot.com/p/Century-...6SV1/203607588

 

No.... it is not a good idea to keep the compressor running without the fan.
It causes the compressor to run under extremely high pressure and excessive heat.

 

You could damage the system running it with no condenser fan, and it wouldn’t cool anyway.
Check the capacitor to see if it’s out of range. It could be just that.

 

You are getting 27 volts at the contactor coil in the condenser and the contactor is not pulling in, sounds like a bad coil as well as a fan motor, HP switch could also be controlling the fan motor.
Geo

 

I think its the fan motor. I used the 2nd unit's Cap on this to see if the capacitor is the issue.
Contactor is working fine after the HP switch was reset. So down to fan motor. It wont rotate easily when i use a stick. I ordered one from HD for $79. I will post once I hookup this next week.