Testing Pressure Switches on Condensing Units

[robsemprini]

Thanks, that was a worthwhile video. I know what they look like and how to check them already, but I still try to learn new techniques…..it would be cool to show the parts close up, for newer guys. But yeah, you're doing a service to the industry with these, good on you, Sir.

[leonardlewis]

Your explanation of why checking continuity over voltage was golden.

[robertalbert]

This would've been a great video, but the unit is 10 miles away and couldn't see anything.

[Trainman]

Great video….question….i have 26 volts going to contactor coil and it didn’t activate because the two sensors were bad. My question is why didn’t the contactor trip?

[jamesblack]

Nice job, very clear and easy to understand

[burtminshew]

I know this is a beginner forum but I had 2 today low/high on a Trane that would shut off the outdoor unit but not blow the ah fuse. Resistance through switches was 2.4 k ohms. It was intermittent and happen once every 10 hours roughly. I bypassed them. Not a service call you want when units run great while you're there.

[cooldude]

How does one change out a pressure switch?

[searchtruth]

The Lennox unit I just repaired at my home has a pressure switch with a reset button on it. The outdoor unit would not power on at all. I pushed the button on the High Pressure Switch and the unit started running again. I felt a distinct click when I pushed the button which I did not feel in subsequent pushing.

[allenchow-dcbr]

High pressure switch should be close .low pressure switch should be open this is correct ?

[sh]

My church Rheem heat pump did not come on when I called for ac. I pressed the contactor at the unit and it just clicked. The defrost board was normal and then after I pressed the contactor, the lights blinked. I didnt read what the code equates to before I left. Am I suppose to find 24 volts at the LP and HP. Can I reset the board to see if it will start?

[normanwick]

My current situation: Split System HVAC compressor and fan do not operate. Indoor unit and thermostat working properly. Capacitor is new. When I depress the plunger on the relay, they both start. There is no 24v to relay coil. Coil has continuity. Pressure switches have continuity. OF1 & OF2 has continuity. What's left? Could the HK32EA007 Board be bad?

[ejonesss]

one way to test the pressure switches is to .

1. to test the high pressure switch just disconnect the fan motor and let the head pressure go high maybe even throw a blanket over the unit to prevent convection cooling.

2. to test the low pressure switch just connect a refrigerant recovery tank to the unit and let the refrigerant out into the tank until the unit shuts off.

the recharge the unit.

if the unit has the low pressure switch connected as a thread on and there is a valve stem similar to a tire you can remove the switch and the unit should shut off.

[michaelclarke]

Thank you for a most helpful video. My condenser (Carrier 3 ton 14 SEER) has no low pressure switch in it. It is possible to have one added? If so do you have any pointers as to what to purchase?

[orionburnham]

Why does he hold his hands so far out in front of him? It's killing me, i literally can't even

[realSamAndrew]

Why would it be any harder to check voltage vs continuity? Either way, you have to get to both sides of the switch. If there is more than one switch, you have to check each one anyway. Continuity may be more useful, but I don't see it being any easier.

[howardtoob]

Thanks for the video. Will the system start and then cut out after a few seconds if the refrigerant is low?

[Fabian]

When your unit is off are both high and low pressure switches supposed to be off ? My unit is short cycling

[OthmanAlikhan]

Thanks for the video =). Leaving some feedback here that you might want to consider related to safety: Apparently some AC units have pressure sensors without Schrader valves so removing them without depleting the refrigerant inside can be hazardous. It would be good to mention some disclaimers related to safety.

[yousefhamed]

i didn't test my switches, but i bypassed them and grounded the contactor the AC still didn't run...could it be the relay board on the unit? I so far changed the main board the capacitor and the contactor...the compressor runs if i push the contactor by hand, I'm running out of things to replace lol

[thomasguillen]

Will a bad high pressure switch .. stop the condensing unit from cycling off when set temperature reached? Thanks...