Unbelievable

[johnridley]

The air conditioner started acting up yesterday. I tried powering it up on the new generator just as a test, that didn't work; the generator sounded really put upon and the compressor just made some noise. It's possible that led to the trouble I'm having but I don't think so, or at least, it only accelerated a problem that would have happened anyway.

There's a relay in the outside unit so that the thermostat can deliver 24vac through a control line and have the 30 amp, 220VAC unit turn on. J noticed yesterday that the compressor was running but the furnace wasn't blowing air. "Stuck relay" I figure. I've never done anything with air conditioners before, but there's gotta be a relay in there. Took the cover off, found a quantity of insanely fast spiders (like, run around the circumference of a 12" square metal box in about 1 second). Yup, relay is stuck. Whack it with a screwdriver, compressor shuts off. Contacts look really fried.

As I said, it's possible that the relay chattered a bit while trying to run on the generator, and maybe got a hundred or two extra cycles added to its life right there, but I think this thing was going to die soon anyway.

So I went online today to find a replacement, so at least when I go to the HVAC shop tomorrow I'll have some idea what I'll be paying.

A Hundred And Thirty Bucks. NO SHIT. For a RELAY. I was figuring maybe $40 or $50 would be the stupidly inflated price for what should cost maybe $25. The HVAC shops charge list if not more so I knew there was no hope there.

Anyway, I went up to eBay and found better (40 amp sealed contact instead of 30 amp open (invite the bugs to crud things up) contacts) new replacement units for $10 each. I went ahead and bought two; I'm betting that these things just are going to fry contacts every 5 or 10 years, so I'll just have a spare.

Luckily it's pretty cool today, and I think we can live without the AC for a few days to save $100. I can just hardwire the thing and switch the compressor on and off with the breaker if it gets hot again before the new relay shows up.

In the past we had a bad solder joint in the control box for the furnace. It took me a couple of years to really find it because it was intermittent, but it cost nothing to fix (I did replace a relay that it turned out was OK, so that cost $8). An HVAC guy I talked to said that they NEVER try to diagnose the insides of the box; they would have replaced it for $400, and it was a couple of hours work so another $250). We've also been through a hot plate ignitor, which cost $45 (I later bought a spare on eBay for $25), but again would have been probably $150 or more to show up and install it. And the guy who sold it to me tried to sell me two, because "these things only last 2 or 3 years" (funny, we're still on #2 after 13 years).

Added to whatever they charge to show up and diagnose (I'm guessing $150), it's no wonder people wind up paying so much for maintenance.

Comments

[c0nsumer.livejournal.com]

I have a weird problem with my furnace where it will, very occasionally, and only during the winter, extinguish the flame, chatter the gas valve, shut off, then relight. I do know it's not the flame sensor, and it seems that if I leave the louvered front off of the furnace it happens less. No idea what it is, though. Maybe I should just try reflowing the points on the board.

[johnridley.livejournal.com]

The chattering sure does sound like a bad connection. In my case the problem was in the higher current connection that drove the relay that ran the flame air blower. When it wasn't working, the blower would not come on, so the symptom was that the control board would be flashing the code for "blower not running" when it detected no overpressure downstream from the blower.

Our furnace has been working fine since I found that cold solder joint and reflowed it.

[isherempress.livejournal.com]

You do realize that you are an exceptional guy, right?

[johnridley.livejournal.com]

Among the general population, sure. Among GT, not nearly as much.

[dave-ifversen.livejournal.com]

I *REALLY* like the old furnace that the landlord has not replaced - it still has a pilot light. When it quit putting out heat last winter, the fix was a simple clean off the white ash around the pilot light. Once relit, it started working fine (and has worked fine ever since). Which reminds me - I should probably get a thermocouple now, so that I will never need it. (It's a repair talisman - if you have it, you will never need it. If you don't have it, it will die at the most inopportune time and be almost impossible to find.)

[johnridley.livejournal.com]

Eh, I think I'll keep the newer furnaces. The only thing that's likely to quit on it is the hot surface ignitor, and $25 on ebay got me a spare. I like the higher efficiency, and also the computer does a darn good job of enforcing a safety protocol; there must be positive pressure downstream of the ignition blower for X seconds before the gas is turned on, etc. And if something goes wrong it gives me blink codes to let me know why it's not working in most cases.