Problem with outside unit

Hello,

I have read a lot of posts but am still having problems. My outside unit will not start, neither fan nor compressor. I replaced the contactor but still won't start. If I manually depress contactor it will start but stops as soon as I let go. I do not have 24 volts at the contactor. Also today I took a look at what must be a pressure switch and the casing of it fell apart in my hand. I tried to manually activate the pressure switch and the compressor and fan started, then there was a spark inside the switch and it would not start again. Could the switch have been the whole problem or do I now have 2 problems? Also I wonder if I may have blown the little circuit board by the contactor? Thanks for any help you can offer. The unit is a Lennox HS-25-411 3 ton

 

A couple of possibilities perhaps you got one of the switch wires against some metal and shorted it out however if your indoor fan is still running that probably did not happen but you definitely need to replace that switch and if your indoor fan is not running look for a small fuse in the board or a circuit breaker on the transformer if you can't find a fuse and your indoor fan is not running you probably burned up your transformer so you will need a transforme and a switch and when you replace them turn off the power and you won't have that issue again

 

Thanks for the reply. The indoor fan is still working fine. So I will try and find a new switch and see what happens.

 

Changing pressure switch is sealed repair and need a tech.

That unit should have a high pressure switch on discharge line and a loss of charge switch.

Also, on diagram I'm looking at, has high and low temp switches.

You could, if the switch did literally fall apart, kill indoor AND outdoor power and bypass the switch. Cut wires, splice, and wire nut together.

If a pressure switch, tech can add a screw on process tee and screw on switch. Don't buy anyone saying charge has to be removed.

It is considered a sealed system repair and is not DIY.

 

Thanks again for your help and I appreciate your concern for safety. I jumpered the switch, and according to the diagram it is the high pressure switch, and now everything is working. How long can I leave it like that until I get a tech out? ( I need about a week)

 

You have at least a week. If you don't get it replaced you could end up with a dead comp or needing a new system.

Trust me Bro, it'll be ok till payday.

 

Many thanks sir. You are a gentleman and a scholar.

 

Not a scholar at all Sir, just a tech enjoying saving people money.

A final word.

"DANGER WILL ROBINSON, DANGER!".

You just bypassed the high pressure SAFETY of your unit. Assuming no dust storms you will be ok until payday as I said.

However, if you do not have this repaired, again as said, you be faced with a very much larger repair bill.

There is a saying in the HVAC industry when something is found incorrect. Pay me a little now, or pay me a lot later. Your choice.

Don't let it go, it can and will bite you.

 

It is only a sealed system repair if the pressure switch is welded into the refrigerant circuit and you replace it if that is the case then you can buy a switch that will screw on to an access port and wire your control wiring to that but first you need to make sure what this switch is doing, it could be high pressure or low pressure you need to check with the nearest distributor of that manufacturer and if you use a screw on switch in place of a welded one you will also want to purchase a brass tee so you will not lose access to the refrigerant circuit (the distributor will know what you are asking for) and buy some thread sealer to prevent leaks and apply it to the bearing surfaces before you thread them together