Need advice: Replace ECM module or entire furnace?

House: Built in mid-1970s. Greater Philadelphia area. Just north of 2000 sq. feet. Purchased in 2009.

Furnace / Blower: Carrier WeatherMaker 8000VS – 58CVA110-20. (80%) Installed 2003.

AC Unit: Carrier 38TXA048 4-Tons – Also installed 2003.

 

HVAC system background FWIW: Between 2009 and 2015 I had to have the AC Unit recharged twice. When the unit stopped cooling a third time, I reached out to a family member who had worked at a HVAC company to recommend a good tech. She did, and the tech said he was able to find a leak on the evaporator coil using a bubble test. He said he said the leak was in a very difficult to reach spot, but he fixed it the best he could and then recharged the system. It worked for a few days and then was blowing lukewarm again. (This was mid-July 2015). He came out again and recharged the system for no-cost - and the AC has been blowing cold ever since. I couldn't understand what happened, but a few people suggested he might have left the Schrader valve open and that's why he recharged it again for free. Oops. Anyway, the blower/furnace had not given me any issues.

The current problem: Last week I realized it was warm in the house. I checked the thermostat and it was set below the house temperature, but the AC wasn't running. I spent the next couple of days troubleshooting. Basically the AC unit outside turned on for a few minutes, but the fan wouldn't turn on at all. I figured out how to read the codes and got a 41 - Blower motor fault. This was above over my head so I called the repair company and got another tech to come out as the other guy left for another job. So last Friday afternoon he spent about two hours trying to figure out the cause of the fault. He wasn't able to so he said they would send out another guy early next week who had more experience with ECM motors. So another guy comes out and in about an hour and a half he tells me it's the motor's ECM module and then he gave me some options:

• Replace the module for $1,100. The part itself was quoted in the neighborhood of $600. I'm not sure if this includes diagnostic labor already completed.

• Replace the existing furnace unit with one of the following units:

1. Payne Multi-Speed Gas Furnace - 80% Single Stage (I'm guessing PG8MEA) for $2200.
2. Payne Variable Speed Gas Furnace - 80% 2-Stage (PG8MVA) for $2650.

 

Money is tight right now, and this just jumped to the top of a very long list of necessary house repairs. So I’d like to make the most cost efficient decision possible (short-term and longer-term). So my basic question is: What is my best option?

 

Considerations / additional questions: The price to replace the module seems a little expensive – that’s why I think it includes the prior diagnostic work. Should I shop around?

Would a Payne furnace work okay with a carrier AC unit?

There’s a lot of info out there about repairing the module with a small part – is this worth investigating?

 

Sorry if this is obnoxiously long. I’d appreciate any information anyone has to offer.

submitted by /u/gawain_is_not_green
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