Defrost cycle on York heat pump

[pgray007]

The defrost cycle on our York heat pump isn’t working anymore, so the unit ices up when in heat mode. I had a “sales tech” from the company that did the install come out and charge $350 to diagnose a bad defrost board, and they want $800 to replace it, all the while trying to sell me on a service plan. It looks like a $100 part that’s essentially a drop in replacement. He also said the low pressure switch may be bad but to my understanding that should cause the unit to lock out rather than affecting the defrost cycle.

I’m going to replace the board myself, anything else I should check or watch out for? Should I replace the sensor while I’m in there? The unit otherwise seems to run fine and I’ve been kicking it over to AC every now and then to deice until I can get the defrost board.


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[kd3pc]

good luck

 

[LS6 Tommy]

I'm kind of rusty, but my recollection is some defrost controllers used both temp or refrigerant pressure to initiate defrost, so a bad LPC may be part of the problem.

Can you post a wiring diagram?

Tommy

 

[Done That]

Most York units are demand defrost meaning they use both coil temp and air temp sensor inputs in the defrost logic. Some of their base units are time temp. The demand sensors are typically thermistors which can be checked by measuring resistance. Demand boards usually have led fault codes for thermistor faults. The time temp uses coil temp input only and are typically just a snap disk analog type sensor.

If unsure and you can readily order the sensor(s) I would go ahead and replace with the board.

 

[tre873]

Our old York system started freezing up when we started using pleated filters. After 2 service calls, we went back to the green sponge filters and the problem fixed itself.

 

[pgray007]

Most York units are demand defrost meaning they use both coil temp and air temp sensor inputs in the defrost logic. Some of their base units are time temp. The demand sensors are typically thermistors which can be checked by measuring resistance. Demand boards usually have led fault codes for thermistor faults. The time temp uses coil temp input only and are typically just a snap disk analog type sensor.

If unsure and you can readily order the sensor(s) I would go ahead and replace with the board.

I can order the sensor easily enough. Can these be replaced without getting into the gas side of the unit? I was kind of assuming that I’d need a tech for the sensor so thought I’d do the board first as I’m equipped (knowledge and tool wise) to change boards but not for refrigerant-related work.

I haven’t pulled a full wiring diagram, but here’s the parts diagram for our unit:

https://www.upgnet.com/Site/Informa.../York_2010A/pdffiles/035-22807-001-b-0310.pdf

The board is called a “defrost time/temp control” so I assume it’s the “smarter” version. I’ll get out there tomorrow and see if there are any blinking lights and see if I can grab resistance across the sensor.


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[Done That]

I can order the sensor easily enough. Can these be replaced without getting into the gas side of the unit? I was kind of assuming that I’d need a tech for the sensor so thought I’d do the board first as I’m equipped (knowledge and tool wise) to change boards but not for refrigerant-related work.

I haven’t pulled a full wiring diagram, but here’s the parts diagram for our unit:

https://www.upgnet.com/Site/Informa.../York_2010A/pdffiles/035-22807-001-b-0310.pdf

The board is called a “defrost time/temp control” so I assume it’s the “smarter” version. I’ll get out there tomorrow and see if there are any blinking lights and see if I can grab resistance across the sensor.


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That's the basic time/temp board. The sensor is item #14 in the parts list you attached. It just clips onto a return bend of the outdoor coil, no dealing with the refrigerant. Location is important, if you replace put it back in the same location as the old one.

Chances are the sensor is OK, they fail so much less often than the board, but while you are going to all of the trouble I still think it's better to replace both parts and know where you are at.....

The board is a pretty easy swap, take a picture of the old setup before you remove any wires, and tag wires as you remove them if you are uncertain at all with what you are doing. Kill power to the indoor unit as well as the outdoor, as the indoor unit transformer powers the outdoor board...don't want to short or damage anything in the process.

 

[pgray007]

That's the basic time/temp board. The sensor is item #14 in the parts list you attached. It just clips onto a return bend of the outdoor coil, no dealing with the refrigerant. Location is important, if you replace put it back in the same location as the old one.



Chances are the sensor is OK, they fail so much less often than the board, but while you are going to all of the trouble I still think it's better to replace both parts and know where you are at.....



The board is a pretty easy swap, take a picture of the old setup before you remove any wires, and tag wires as you remove them if you are uncertain at all with what you are doing. Kill power to the indoor unit as well as the outdoor, as the indoor unit transformer powers the outdoor board...don't want to short or damage anything in the process.

Excellent.... I’ll replace the sensor as well and let you know how it goes. Seems like a pretty straightforward job and I really appreciate the guidance!


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[u3b3rg33k]

check out the Emerson/White Rogers Universal Heat Pump Defrost Control 47D01U-843. so long as your gear is single stage it should do the trick.

can be set for demand or timer based defrost operation. might be nice if you have a timer model and live where you have low average winter dewpoints.

Our old York system started freezing up when we started using pleated filters. After 2 service calls, we went back to the green sponge filters and the problem fixed itself.

"media filter" 4" thick or the 1" pleated? the 1" are known for causing(being) restrictions. I have an 2200 model media filter (5" thick). lower pressure drop when dirty than most 1" are new.

 

[tre873]

check out the Emerson/White Rogers Universal Heat Pump Defrost Control 47D01U-843. so long as your gear is single stage it should do the trick.

can be set for demand or timer based defrost operation. might be nice if you have a timer model and live where you have low average winter dewpoints.



"media filter" 4" thick or the 1" pleated? the 1" are known for causing(being) restrictions. I have an 2200 model media filter (5" thick). lower pressure drop when dirty than most 1" are new.

It was the 1" pleated filter. After I thought about it some more, it wasn't the same scenario as the OP, mine would trigger the LED fault light. Too many defrosts in a set amount of time.

 

[pgray007]

Replaced the board today. Took all of 10 minutes. Really disappointed in the HVAC company that did the install and quoted $770 to replace the board, in addition to the $350 service visit and diagnostic fee. I don’t begrudge anyone for making money, since I’m also essentially in the business of selling specialized knowledge, but their work is pretty shoddy and $1100 all in seems excessive. They lost a few screws for the panel cover, and rather than replacing with the correct machine screws, used self-tapping screws that stripped out the factory holes on the heat pump.

On the furnace in the attic, they put the transformer inside the unit on the underside of the top cover, with a single self tapping screw that’s half-assed at an angle, so the transformer (connected to a 50A circuit for the aux heat) is dangling by a single screw and will fall into the unit if the screw fails, creating a nice fire hazard. All this makes me respect tradespeople that actually care about their work all the more. It’s pretty obvious as I learn more about this stuff and repair things around the house which trades gave a **** when they built our house and which didn’t care.


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[bonneyman]

Replaced the board today. Took all of 10 minutes. Really disappointed in the HVAC company that did the install and quoted $770 to replace the board, in addition to the $350 service visit and diagnostic fee. I don’t begrudge anyone for making money, since I’m also essentially in the business of selling specialized knowledge, but their work is pretty shoddy and $1100 all in seems excessive. They lost a few screws for the panel cover, and rather than replacing with the correct machine screws, used self-tapping screws that stripped out the factory holes on the heat pump.

On the furnace in the attic, they put the transformer inside the unit on the underside of the top cover, with a single self tapping screw that’s half-assed at an angle, so the transformer (connected to a 50A circuit for the aux heat) is dangling by a single screw and will fall into the unit if the screw fails, creating a nice fire hazard. All this makes me respect tradespeople that actually care about their work all the more. It’s pretty obvious as I learn more about this stuff and repair things around the house which trades gave a **** when they built our house and which didn’t care.


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I feel your disgust. As a contractor I saw lots of examples of AC people just screwing their customers. Though there are some competent, honest techs out there (i.e. I'm one of them), the majority of service people out there are not properly trained and/or focused only on the money. Makes for many unhappy customers.

 

[pgray007]

I feel your disgust. As a contractor I saw lots of examples of AC people just screwing their customers. Though there are some competent, honest techs out there (i.e. I'm one of them), the majority of service people out there are not properly trained and/or focused only on the money. Makes for many unhappy customers.

Any advice on how you find the good ones? I used a guy from Craigslist to help me with my mini split who was great, so I’ll probably use him again when I get in front of my skis (I don’t want to learn how to work on the refrigerant side of HVAC but can work a multimeter and screwdriver all day long). Seems the independent/small shop guys do the best work, but $300 a whack to evaluate their skills is an expensive evaluation process.


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