Help me diagnose an HVAC problem

[TimR]

My wife volunteered me to look at a friend's broken AC unit. I'm not a tech or a mechanic but I said I'd give it a shot, maybe it's something simple. The friend has very little income. So I spent the afternoon in a very cramped hot attic, without figuring it out. I weigh 135, and if it was 136 I might not have got up there.

Here's the (long) story. It's a small unit that serves only a small upstairs, gaspack for heat and cooling coil. According to them, it was working fine until the "pan" rusted through and the ceiling got wet and fell. Someone replaced the pan with a slightly larger plastic one. And the unit hasn't come on since.

So I thought, well sometimes a pan has a float switch, maybe they just left a wire off. I can at least take a look.

Here's what I saw: nice clean new platic overflow pan with PVC pipe glued in, leading across the attic to unknown. Another PVC pipe coming out of the cooling section, with the typical short trap, and again across the attic to unknown. Can't really get up on that side, I'm looking through a handhole. Thermostat is about 4 feet below the unit, it has five wires. One wire goes to a two conductor wire that roughly tracks the drain pipes to unknown. Thermostat is set to Cooling, Fan On, but neither is happening. Thermostat wires connect to the main part of the unit with the fan and heat, no wires seem to connect over to the cooling section.

So here are my questions:

1. If the overflow pan failed, the internal pan must have failed or plugged first. Should that trip the unit? It didn't, obviously.

I could not find where the condensate is supposed to drain to. The house has a crawl space, no basement. The downstairs unit does have a condensate drain I could find. I don't have equipment to blow out condensate lines so it seems we're going to need a pro. But it seems that alone doesn't stop the unit. (Who puts in condensate lines without a way to unclog them?)

1. The thermostat wires are all connected with wire nuts right at the hand hole, the easy part of this to access. I can take meter readings; if so what should I look for?

1. What am I missing? This needs to go to a real mechanic soon, but I'm willing to go back one more time to keep the peace.

[invalid unparseable]

I am guessing here. The original metal pan rusted, that means the original metal pan was not stainless steel. Since the replacement pan is plastic instead of ferrous metal and the air conditioner wouldn't come on, there is a good chance the air conditioner was designed to detect the presence of the original ferrous metal pan with a magnet. Try to use a similar ferrous metal pan to see if the air conditioner will come on. If you cannot find a similar ferrous metal pan, then try to locate the air conditioner's magnet by feeling around with a screw driver or some ferrous metal inside the cavity where the metal pan would push against the walls. If you can find the magnet, then you can glue a piece of scrap metal there, like the lid of a sardine can, to fool the air conditioner to think that the original ferrous metal pan is there.

[TimR]

You don't understand, or I haven't explained clearly.

The plastic pan is an overflow. It is completely underneath a sealed coil unit, not in contact with it. There should be an internal pan inside under the coils that catches the condensate. Nobody would have the actual condensate pan open to the air, dust, critters, etc.

And there are two PVC condensate drain pipes, one from the coil unit, and one from the overflow pan. But when the overflow pan rusted the ceiling below was damaged. So, either we had a simultaneous clogged internal pan and a failed overflow pan, or - and come to think of it probably more likely - the internal pan failed or clogged years ago. Because of laziness, frugality, really bad access in this cramped attic space, who knows - they just removed a plug and let the internal pan flow into the external overflow pan. Huh, I wonder if that tube goes to the soffit - I didn't think to look there.

I have never heard of a magnetic switch like you describe. I have seen many cases where the pan fills and a float switch is tripped.

[invalid unparseable]

I have two different makes of portable dehumidifier with float to detect water level in the tray, and the mechanism detecting the float reaching the top is a magnetic switch inside the unit. The float itself is plastic with a tiny embedded magnet. I guess a magnetic switch is more sensitive than a mechanical switch.

[invalid unparseable]

I have a portable air conditioner with a built-in circuit breaker in the power plug. It will trip if the air conditioner is drawing too much current (usually during compressor retarts). You can check if that air conditioner also has a circuit breaker built into the power plug too.

[invalid unparseable]

They can make 15A circuit breaker small enough to fit into the power plug now. I cannot find on the internet a photo of the power plug of my air conditioner. This is a replacement power plug with circuit breaker sold on Amazon:

[bud--]

With further work in the hot attic your weight will go down and you will fit better.

Have you got power at the unit? Was a circuit breaker turned off to install the pan and not turned on? is there a breaker turned off?

I haven't worked on an attic unit - don't know if they might have protection from water accumulating. Never seen it on units I have worked on.

A common thermostat wiring code is Red - 24VAC power to tstat Green - to fan relay White - runs heat Yellow - runs AC

5th wire might be other side of 24V power - could be used for electronic tstat

With fan, cooling and heat off with this wiring red to green connection runs fan red to white connection runs heat red to yellow runs AC

If there is power, with fan, cooling and heat off with this wiring there should be 24V between red-green, red-white, red-yellow you can check this at the tstat terminals

I assume there is an outside unit with compressor/condenser. There should be 2 (24V) wires to it (likely your "two conductor wire").

There doesn't need to be wiring to the evaporator coil.

Whoever installed the pan may have liability.

Attic unit will be hard-wired.

Power plug gizmo is likely AFCI

You need a float switch on a portable dehumidifier because it collects water. The attic unit shouldn't collect water.

[TimR]

Thanks. That helps me think through this.

I'll go back and check voltages. It didn't occur to me that the mystery wire went to the outside unit. Doh! That would have been a tech's first thought I imagine. It also makes sense that the condensate drains I couldn't find are probably in the soffit where that wire comes out, so should be easy to find - maybe very hard to clear if clogged.

I did check the breaker - been there done that too many times. But power to the unit? A little hard to check, but I will see if hot to thermostat has 24 volts. Thermostat is on showing temperature but it could have a battery.

If there is no wiring to the evaporator coil, then my idea of a safety interlock is clearly mistaken.

To recap simpler: Cooling was running, ceiling fell, occupant had leaking overflow pan replaced but unit was not opened, unit would not restart.

She also mentioned to me that the downstairs unit, a heat pump, cooled fine but heat did not work so they use space heaters. Sigh. Not going to touch that one. Both thermostats were replaced at the same time, sometime in the past.

[bud--]

For purposes of what you are doing, if the pans are not wet it shouldn't make any difference if the drains are clogged.

(Not mentioned - there should be 2 refrigerant lines from the compressor/condenser, one much smaller than the other.)

Could be battery or could be 24V from red to 5th wire (blue?).

If it had a limit it probably wouldn't shut down the fan or heat.

Air conditioning could have low pressure limit. If refrigerant leaked it would shut down air, but not fan.

There should be a "disconnect" at the unit, which would be like an ordinary wall switch. Trace the power wiring coming into the unit.

[bud--]

Amazon: "GFCI Replacement Plug for Pressure Washer Pool Pump 15Amp 3 Prong Circuit Breaker Outdoor Waterproof Auto-reset 120V"

Pool pumps require a GFCI

Don't know about pressure washers, but GFCI is reasonable.

"Circuit breaker" probably means if the GFCI trips it will break the circuit.

Does not say anything about tripping at 15A.

Does not say it is for window air conditioners.

My window air conditioner as an AFCI plug. I think it is common on those plugs.

A picture of the plug on your AC wouldn't indicate what it is for. Specs or manual would.

(Amazon plug has "test" and "reset" buttons - very unlikely it is "auto-reset".)

[invalid unparseable]

I have searched high and low, and finally found a photo of the replacement part of the power cord to my Danby Portable Air Conditioner (model DPAC10011)

You can see two buttons (large and small) on the back of the power plug by point your mouse at the picture to zoom in.

The only time the circuit breaker had tripped (rarely) was when the compressor motor was trying to restart (restarting too quickly in hot weather without relaxing enough pressure). The outer housing of the portable air condition is completely plastic. There is no reason to have a circuit breaker built into the power plug other than to prevent overheating the entire electrical wiring all the way to the electrical main due to compressor hard start.

This is the portable air conditioner:

[TimR]

Yup. There was no voltage on the hot pin at the thermostat. Thermostat had a couple AAA batteries so it still lit up.

Power wiring did go into an ordinary wall switch. Turned it on, everything came back on. Either the pan guy turned it off, or bumped it by accident; pretty tight quarters up there, and working through a small access hole.

As always, better to be lucky than smart.

[bud--]

I see lots of power cords, but none with 2 buttons.

GFCI plugs exist and have 2 buttons. Your Amazon plug is GFCI. AFCI plugs exist and have 2 buttons. Circuit breaker plugs - I have never seen one.

But you just assume it is a circuit breaker. The picture establishes nothing. I see no reason to believe it is a circuit breaker.

Don't know where you live, but everywhere I have been circuits are fed by circuit breakers or fuses that open on overload or short. I think that is what they are for. Plastic is relevant?

Says nothing about any kind of protection in the plug.

It does have: "What are the standard watts and amps used?" "Information pertaining to watts and camps [Canadian amps?] can be found on the rating plated [metal lettering is plated onto the plastic side?] located on the side of the unit."

All you have to do the get the amp/watt rating is to buy one of them.

A manual is available at:

It also says nothing about the plug and gives no amp/watt ratings. This unit does have some amazing specs though: Width 0" Unit 0.00 kg Shipping 0.00 kg

I see no reason to think the plug has a circuit breaker. Lots of reasons to think it is an AFCI. My AC has an AFCI plug. I think they all (in the US) do now.

[invalid unparseable]

I live 1. PRESS TEST BUTTON, UNIT SHOULD TRIP

1. PRESS RESET BUTTON FOR USE.     DO NOT USE IF ABOVE TEST FAILS

The only times the circuit breaker tripped was at the moment the compressor attempted to restart. It makes quite a loud "click" when it trips.

[bud--]

"NEC 440.65 Protection Devices Single-phase cord and plug connected room air conditioners shall be protected with one of the following factory installed devices: (1) Leakage-current-detector-interrupter (LCDI) (2) Arc-fault circuit interrupter (AFCI) (3) Heat detecting circuit interrupter (HDCI) The protection device shall be an integral part of the attachment plug or be located in the power supply cord within (12 in.) of the attachment plug."

(1) and (2) were required in the 2002 NEC (3) was added in the 2017 NEC

[micky]

How did the topic become portable airconditioners? The OP's friend's AC is in the attic. They don't have portable AC's in the attic, with external pans.

[invalid unparseable]

I was bringing to attention that the cause of that attic air conditioner problem might be a tripped fuse at the plug. I was almost correct. That attic air conditioner had a wall switch that wasn't even turned on. I feel like a genius.

[invalid unparseable]

Where do you live? You post has a time stamp that's 30 minutes off from my clock (not counting the hour). Or is there a problem with your computer's clock?

[Ralph Mowery]

Always check the simple things first. I worked at a large factory and found out that some of the operators were slightly dumber than a box of rocks. Like the call I got that a machine would not start. Told the operator to press the Green button instead of the red one.

[invalid unparseable]

Whose idea was it to use the green button to turn on some industrial machinery that can possibly drag you into the machine, shred you, and spit you in tiny fragments out the other end? They should have used the red button for "ON".