AC High Pressure switch

[Ralphxj]

Ok, it's 89 here and when I tryed to turn on the AC today, I got lots of hot air!! After doing a bunch of checking, the fan on the outdoor unit isn't coming on! After more searching I have tracked the issue to the high pressure switch, which some friendly mice have chewed the wires off of!! They are chewed flush at the bottom so there is no chance of reconnecting them. When I jump the wires, everything works like it's suppose too.

Can the pressure switch be removed without dumping coolant? Or does the entire system need emptied so the switch can be swapped? Just don't want to waste my time buying a switch if I can't swap it myself and need to call for a hvac guy.

 

[rlitman]

Depends on the system. Can you post a pic?

 

[wagzilla]

Depends on the system. Can you post a pic?

A picture would be nice

 

[JJThrasher]

Most of the switches have a valve below them so only a minimal amount of refrigerant is lost. Without seeing the car I'd say you're fine to swap them.

 

[zmaxmotorsports]

Most of the switches have a valve below them so only a minimal amount of refrigerant is lost. Without seeing the car I'd say you're fine to swap them.

I think hes talking about a condensing unit on a house.

 

[zmaxmotorsports]

Depending on the age of the condening unit if it doesnt unscrew from a service port on the liquid line Id probably just leave the wires wire nutted together.
If it unscrews and has a shrader valve/service port under it Id just replace it.

 

[Ralphxj]

Depending on the age of the condening unit if it doesnt unscrew from a service port on the liquid line Id probably just leave the wires wire nutted together.
If it unscrews and has a shrader valve/service port under it Id just replace it.

I'll get a photo when I get a chance. I've lived in the house 6 years and it was probably 5+ years old at that point if I can just leave the wires connected for now I'll do that to get through this hot weekend.

 

[zmaxmotorsports]

I'll get a photo when I get a chance. I've lived in the house 6 years and it was probably 5+ years old at that point if I can just leave the wires connected for now I'll do that to get through this hot weekend.

If it doesnt unscrew Id just leave it,A 10 plus year old system isnt worth the cost of pumping all the freon out/replacing part of the line and new switch/then having the system recharged if you have to pay somebody to do it.

 

[Smoky14]

I had mine bypassed all summer, changed it in the fall. It did have a check valve in the base and I lost very little charge during the change..wear gloves!
Smoky

 

[Big Daddy Chop Shop]

No unit with a UL listing should have a valve below the high pressure switch. Now, most are field added in residential applications, HOWEVER, a lot of high pressure switches do not even have a valve depressor on them. It is indeed a gamble. Furthermore, there is a relief built into the system which will dump the charge should your pressure reach an unsafe level.

410a is at about $3 per pound wholesale, R22 is at about $14-18 per pound wholesale.

My honest recommendation.......call the man. You think its expensive to hire an pro, see what an amateur costs- pay me now or pay me later.

 

[LS6 Tommy]

Furthermore, there is a relief built into the system which will dump the charge should your pressure reach an unsafe level.

I can't honestly say if any 410a systems have them (never seen one), but no residential R22 unit has had an external relief valve since about 2 decades before I started in the industry. They don't need one. All hermetic compressors have internal bypass valves that open if the discharge pressure gets too high to recirculate from the discharge back into suction.

Tommy

 

[zmaxmotorsports]

No unit with a UL listing should have a valve below the high pressure switch. Now, most are field added in residential applications, HOWEVER, a lot of high pressure switches do not even have a valve depressor on them. It is indeed a gamble. Furthermore, there is a relief built into the system which will dump the charge should your pressure reach an unsafe level.

410a is at about $3 per pound wholesale, R22 is at about $14-18 per pound wholesale.

My honest recommendation.......call the man. You think its expensive to hire an pro, see what an amateur costs- pay me now or pay me later.

Its atleat an 11 year old system according to op,when did 410a come on the market?

 

[JJThrasher]

I think hes talking about a condensing unit on a house.

Side affect of being a mechanic I guess. My bad. Best of luck OP.

 

[brewchief]

Its atleat an 11 year old system according to op,when did 410a come on the market?

Late 90's early 2000's depending on brand, carrier and Lennox had it out first with some brands not having 410a equipment until just a few years ago.

 

[zmaxmotorsports]

Late 90's early 2000's depending on brand, carrier and Lennox had it out first with some brands not having 410a equipment until just a few years ago.

I remember carrier having puron,couldnt remember when it came out though.

 

[Big Daddy Chop Shop]

I can't honestly say if any 410a systems have them (never seen one), but no residential R22 unit has had an external relief valve since about 2 decades before I started in the industry. They don't need one. All hermetic compressors have internal bypass valves that open if the discharge pressure gets too high to recirculate from the discharge back into suction.

Tommy

yep, that is one and the same.

 

[LS6 Tommy]

yep, that is one and the same.

OK, I follow. When you said "dump the charge" i thought of the old releif valves that literally released refrigerant to the atmosphere. Not really related, but some compressors on refrigeration systems have discharge service valves right on the head & they're UL listed.

Tommy

 

[txst]

No unit with a UL listing should have a valve below the high pressure switch. Now, most are field added in residential applications, HOWEVER, a lot of high pressure switches do not even have a valve depressor on them. It is indeed a gamble. Furthermore, there is a relief built into the system which will dump the charge should your pressure reach an unsafe level.

410a is at about $3 per pound wholesale, R22 is at about $14-18 per pound wholesale.

My honest recommendation.......call the man. You think its expensive to hire an pro, see what an amateur costs- pay me now or pay me later.

If the system uses R410A, it can not have a valve core under the switch as it is a safety device per U.L. If the system uses R22, it is possible to have a valve core, as it would only be for reliability improvement, not safety, but it may not - it depends on the manufacturer. As Big Daddy said, many of the screw-in high pressure switches do not even have a valve core depressor. The compressor does have an internal bypass valve if the differential pressures become too high, but reliability can be negatively impacted if it continually is activated, and it does not satisfy the maximum burst pressure requirement for the copper or aluminum heat exchanger tubing if you bypass the pressure switch and the condenser fan fails on an R410A system.