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Discussion Starter · #1 · (Edited)
Hi,

I have a Goodman packaged unit outside (AC/heat), model gpg1336090m41ad.

Early in the morning we realized the heat wasn't working. My thermostat (Nest gen 3) indicates that it is heating, however cold air is being blown through the vents in the house.

I've done some troubleshooting and listed my steps below:

  • I flipped the main breaker to off and then back on. I confirmed that the unit is getting power.
  • I turned the thermostat down and confirmed that the unit turns off.
  • When I turn the thermostat up (and the thermostat indicates it is heating) I hear the furnace turn on. It sounds like the furnace is working as I can hear air circulating, and air is coming out of the exhaust vent on the unit.
  • I removed the cover to look at the control board. The control board has a solid red light when the thermostat is turned down and the unit is idle.
  • When I turn the thermostat up, the control board light flashes twice, pauses, flashes twice again, and so on.
  • I confirmed that the gas is flowing by checking the gas at our fireplace in the house.
  • I looked at the gas line valve that runs to the furnace and it is open and doesn't appear to have been touched in a long time as it is very rusty.

A quick Google search about the flashing light on the control board seems to indicate a problem with the draft blower or pressure switch:
"Two flashes indicate the draft blower supplying combustion air to the furnace is not working or your furnace has a short in the pressure switch safety circuit." - from hunker . com

Unfortunately I'm not sure how to get access to the pressure switch on this packaged unit. It is not behind the main panel that I removed to access the control board.

So my question is, does this indeed sound like an issue with the pressure switch, or, at least, is replacing the pressure switch a good first step? If so, how do I access the pressure switch?

Or, should I resolve to call an HVAC tech?

I've attached a couple pictures if they help.
 

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The pressure switch is in the burner compartment.
To check this, you’ll need a meter and you’ll be working around live gas and electricity.
Is the pressure switch actually closing? Is the tubing broken or off of any ports? Is anything clogged up?
 

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Discussion Starter · #3 ·
I'm having some issues accessing the burner compartment. The gas line that goes through the compartment panel is preventing the panel from being removed. Looks like that section of the gas line will have to be removed.

I also do not have a meter. Looks like I'm going to need to call a technician. Thanks for your reply!
 

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Sure thing. Just use someone trustworthy. What we refer to as “sales techs” are running rampant in the industry right now. People that don’t have much technical ability, and all their training focuses on selling rather then repairing.
If it’s been a while since the unit had a checkup, probably a good time to get that done as well. The unit should be checked out at least once per year.
 

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I think its the second panel to the left of the of the one you posted a pic of that has the pressure switch in it.
 

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Discussion Starter · #6 ·
I had an HVAC tech sent via the home warranty company out, and he removed the second panel to the left, behind which I saw the pressure switch. I was attempting to remove the wrong panel.

The tech removed the pressure switch and said there was water in it, and said the cause of that was that the heat exchanger was cracked. He said the cause of the crack was that the valve was never swapped from LP to natural gas, so it was basically consuming 3x more gas than it should have been, which somehow caused a crack. He also showed me some rust on the heat exchanger as more evidence of moisture getting into the system.

He indicated that the entire unit would likely need to be replaced, or just the heat exchanger, depending on what the warranty company wanted to cover. I didn't have a lot of confidence in the tech and he seemed to be enthusiastic about getting a big job through the warranty company.

Does this all sound plausible?
 

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did you own the place when the unit was originally installed, mainly that the LP valve was never switched to NG? That is a major error.

Also, do you know how old is the unit?

Traditionally, home warranty policies do like to lowball, but are there any exclusions in your policy for previous installs or repairs w gross negligence, like not switching the unit to the new fuel type?

good luck
 

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No, it doesn’t. Home warranty companies often hire service companies based on how cheap they are.
Units rarely come set up for LP. If it were never set up for LP instead of natural gas would be more plausible.
Rust on the heat exchanger is common in a package unit.
Moisture in a pressure switch could be a long list of things.
Where was the crack he showed you?
 

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Discussion Starter · #9 ·
He didn't show me a crack. I was standing out by the unit with him the entire time, until it came time to pay, and I went inside with his partner who was collecting the service fee. While I was inside, he apparently confirmed that the LP valve was never replaced with the NG valve.

Before that, while outside, the tech removed the top of the unit, hoping to be able to determine if there was indeed a crack, but couldn't get access to what he needed without a lot more effort, which he didn't make.

He took off the pressure switch, went to his truck with it, and when he returned he said there was water inside. He showed me some rust under one of the panels, picture attached, that he said also provided evidence that moisture was getting in the system, which he said would be caused by a crack in the heat exchanger.

I did not own the house when the system was installed. It is a 2006 unit. The tech said they would not report to the home warranty company that the previous install was done improperly, because then they wouldn't cover the cost of repair.
 

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Offensivelybad wrote:

"He took off the pressure switch, went to his truck with it, and when he returned he said there was water inside"

Why did he have to go to his truck to tell you this? Also, did he show you the moisture or just tell you it was there?

Is it just me, or does this tech seem a little bit off ?
 

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Your unit came equipped for natural gas. It says right on the gas valve what conversion kit to use when converting to LP. Not from LP to natural.
Your burning natural gas, correct?
It also says on the manifold which LP gas conversion kit to use.
 

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Discussion Starter · #15 ·
He didn't show me the moisture. I was talking to his partner/company owner when he went to the truck and didn't think much of it.
 

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OB,

Do you even live in an area [rural where gas lines didn't exist] where there are LP tanks? I live in city w NG, but I have a ranch w a 250 gal LP Tank. My stove and water heater are both set for LP. I converted the stove to LP, but bought the Rheem Water Heater already configured for propane.

If your area did not provide options for LP in 2006, and that unit was installed new w NG as r-neck stated, [not moved from a place in the country w propane], then how did it get changed from NG to LP ?

Is everything reinstalled as before tech came? If so, it might be worth your while to get a second opinion. Or, did the first tech "fix anything" or leave as is?
 

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R-neck wrote:

"So your warranty tech either doesn’t understand how your unit works, or is just trying to sell you unnecessary parts. Moisture in a pressure switch doesn’t automatically indicate a cracked heat exchanger."

The tech could have made a mistake, but I'm more on the pessimistic side that he either doesn't know what he's doing or misleading you...as noted by r-neck.

I think it's a hard call to guess on the pressure switch and moisture unless you are right there and seeing it...I would be inclined to get someone else to look at your unit. I know it's a another fee, but it be worth it to get an honest or more well advised opinion...
 

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Discussion Starter · #20 ·
As far as I know the entire city has access to NG, though outside of the city it is probably hit or miss.

I will contact another HVAC company that was recommended to me, but not sure how that will work with the home warranty company. I guess I'll find out.

Thanks for your help!
 
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