Low pressure switch - cutoff pressure for R134a

[Ron]

My understanding is the high side would be surprisingly high and the low side would be surprisingly low if the orifice is clogged.
...

The low side would go negative, I.E., show vacuum.

[82DMC12]

The low side would go negative, I.E., show vacuum.

So it sounds like that's probably not it.

I still like my idea of a partially obstructed evaporator. Or there is something going on with the vacuum flap actuators and outside air or heater air is being mixed with the cold air.

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[Michael]

So it sounds like that's probably not it.

I still like my idea of a partially obstructed evaporator. Or there is something going on with the vacuum flap actuators and outside air or heater air is being mixed with the cold air.

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Unless there is a major break, I'm sure the heater flap is closing as I can hear it smack shut.

I'm going to borrow my neighbor's borescope camera and take a look at the evaporator area and see if maybe there is some blockage...I can't imagine it's got standing water in it as I would have surely smelled it by now.

The only other idea I have is maybe the expansion tube is missing altogether.

[82DMC12]

Unless there is a major break, I'm sure the heater flap is closing as I can hear it smack shut.

I'm going to borrow my neighbor's borescope camera and take a look at the evaporator area and see if maybe there is some blockage...I can't imagine it's got standing water in it as I would have surely smelled it by now.

The only other idea I have is maybe the expansion tube is missing altogether.

If the expansion tube were missing, you would not feel any cold temp on the return side of the compressor. Everything would be hot , the gauges would equalize, and the compressor would be knocking from taking on hot liquid refrigerant.

Maybe leaves, etc packed up inside the evap box.

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[Michael]

That's good to know! Nothing would make me happier than to see a bunch of leaves or some stray piece blocking the evaporator fins. Maybe I'll tackle that tomorrow afternoon.

[dmcman73]

That's good to know! Nothing would make me happier than to see a bunch of leaves or some stray piece blocking the evaporator fins. Maybe I'll tackle that tomorrow afternoon.

If it does turn out to be leaves and/or other debris in there, when I finished rebuilding my HVAC box, I installed a 16X16 stainless steel wire cloth over the air intake under the cowl to keep all of that out. I just cut it to size to fit over the rectangular opening and just laid it over it, the cowl holds it in place once you re-install it. If you want, you could add a few dabs of RTV to hold in in place as well. This is what I used: https://www.mcmaster.com/85385T65/

[82DMC12]

If it does turn out to be leaves and/or other debris in there, when I finished rebuilding my HVAC box, I installed a 16X16 stainless steel wire cloth over the air intake under the cowl to keep all of that out. I just cut it to size to fit over the rectangular opening and just laid it over it, the cowl holds it in place once you re-install it. If you want, you could add a few dabs of RTV to hold in in place as well. This is what I used: https://www.mcmaster.com/85385T65/

I did the same thing. I removed my cowl to replace it, and found a surprising amount of pine needles, leaves, dirt etc down there. I put that screen someone was selling under my cowl , same thing just has some edge trim on it to make it look pretty.

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[dmcman73]

I did the same thing. I removed my cowl to replace it, and found a surprising amount of pine needles, leaves, dirt etc down there. I put that screen someone was selling under my cowl , same thing just has some edge trim on it to make it look pretty.

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I made my own and made it with the edge trim, but found that the edge trim put pressure on the cowl and it also blocked water from draining so I removed it. Once the wire cloth is laid out and the cowl installed, it holds it nicely and you can't even see the edges of it (as long as you cut it where it isn't too wide and it it sticks out from under it).