Any ideas where to look first for suddenly non-operating heat pump?

Typical!
In AZ we have the Air Handler in the attic and the Heat Pump sitting on some square beside the building.
Shut off the AC last winter, and when went to turn it on this one time, nothing happened. Well, except the fan came on, but no big power hum, no fan blade inside the heat pump running.
Just as a check I measured all the voltages coming from the the thermostat out through to the unit, and they all seem correct. OFF no voltage, ON 26 Vac, yet unit doesn't come on. There is a distinct power hum, but nothing happens.
I turned OFF the 220Vac going to it, and measured the voltages around the huge relay right at the access and was disappointed to find almost nothing there. I expected the relay[whatever it's for] to be powered. Perhaps that's the key.
Inside the access panel lid is atype of schematic. One interesting item caught my attention 'low pressure switch' so I thought perhaps the unit has lost its charge and the swicth won't come on to prevent damage when it's not properly charged. But I don't know much about HVAC units. There are three access spigots for measuring/filling I think all right under the access panel.
Anybody out there with a bit of tutorial to help? Like what pressure range should be there, what to do if the pressure is too low, etc etc.
I've got two other identical, operating units to do comparisons to, but it still helps to know WHERE to look.
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You do realize that federal law requires EPA certificate to measure the "spigots"? Fine, imprisonment, all that happy stuff if you do.
Christopher A. Young Learn more about Jesus www.lds.org .
Typical!
In AZ we have the Air Handler in the attic and the Heat Pump sitting on some square beside the building.
Shut off the AC last winter, and when went to turn it on this one time, nothing happened. Well, except the fan came on, but no big power hum, no fan blade inside the heat pump running.
Just as a check I measured all the voltages coming from the the thermostat out through to the unit, and they all seem correct. OFF no voltage, ON 26 Vac, yet unit doesn't come on. There is a distinct power hum, but nothing happens.
I turned OFF the 220Vac going to it, and measured the voltages around the huge relay right at the access and was disappointed to find almost nothing there. I expected the relay[whatever it's for] to be powered. Perhaps that's the key.
Inside the access panel lid is atype of schematic. One interesting item caught my attention 'low pressure switch' so I thought perhaps the unit has lost its charge and the swicth won't come on to prevent damage when it's not properly charged. But I don't know much about HVAC units. There are three access spigots for measuring/filling I think all right under the access panel.
Anybody out there with a bit of tutorial to help? Like what pressure range should be there, what to do if the pressure is too low, etc etc.
I've got two other identical, operating units to do comparisons to, but it still helps to know WHERE to look.
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On Jun 17, 5:06 pm, "Stormin Mormon"

Did NOT know that! I guess that explains why the high security plastic covers on those spigots. They look just like the ones on your car.
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They act a lot like car valve stems. Different size, though.
Christopher A. Young Learn more about Jesus www.lds.org .
Did NOT know that! I guess that explains why the high security plastic covers on those spigots. They look just like the ones on your car.
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Robert Macy wrote:

Looks like you'll have to go into your attic to fix it.
(again - the stupidity of putting even part of your hvac system in the attic !)
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huh?
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It's a homelessguy thing. Just ignore him.
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On Jun 17, 7:46 pm, snipped-for-privacy@gmail.com wrote:

Agree. There should be 240V coming in to one side of the relay/ contactor with the power turned on. And there should be 240V on the load side of the contactor with the power on and the relay energized. If he's OK with safely measuring that, then I would do that. If the power hum is coming from the contactor when the thermostat turns it on, that's normal. Could also verify that the contactor pulls in by listening to it while someone else activates the thermostat. Just be aware that most thermostats have a 5 min lockout, where if it's been activated, then turned off, it won't turn on again for 5 mins to protect the compressor.
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wrote:

Has anyine thought about a blown fuse in either side ot the 230V line??? When my outside/compressor unit blows a fuse, depending on which side of the 230V line blows, the 24V relay operates, but the compressor does not come on, and depending on which side of the 230V lines is blown, the fan which operates on 115V may not come on either.
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wrote:

The breaker for the 220Vac 30A to this AC Heat Pump has never gone off. One of the operating units makes the breaker super hot so I know there's current when they're working. This one has absolutely nothing going on.
The Air handler in the attic has 220Vac 20A to it, and the fan activates normally.
What caught my attention in the outside unit is the presence of mechanical relays down inside. I've always suspected the reliability of relays. sticking off sticking on something always not working right. So I applied the standard TV repair technique. 'Gently' shifted it around, NOT! no indication of any change so must be something more wrong there.
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Super hot breaker? That doesn't sound right. I'd be checking for a loose/corroded connection at the breaker. Or possibly a bad breaker.
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Phone book: Air Conditioning systems, service and repair.
Christopher A. Young Learn more about Jesus www.lds.org .
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wrote:

Thanks, about the timing. Knew there should be some type of lock out, didn't know how long. I tried things over several hour period with at least half hour between tests to try and make certain didn't trip over any of these 'lockouts'
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On Jun 17, 4:46 pm, snipped-for-privacy@gmail.com wrote:

My thinking: the 24 Vac coil should have been activated, reading the voltage at the coil should have seen it try to turn on. The 24 Vac is supplied from the attic unit comes in under different breaker. The 220Vac is to supply the 'husky' stuff.
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You verified that you have 24V at the contactor relay. See if you have 240V on the load side of the contactor relay with thermostat calling for cooling. If you do, then it's something with the compressor. If you don't then work your way back up the circuit.
Also, haven't worked on one of these in a while, but it seems to me the fan in the outside unit should be running even if the compressor isn't starting? Anyone?
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Most refrigeration wholesale houses. Bring your EPA card. You aren't likely to find Freon, any more. I do haves some, a rather old 50 pound container. You may be able to find Forane, Isotron, Genetron, or some other brand. I havn't seen Freon for sale, in ages.
Christopher A. Young Learn more about Jesus www.lds.org .
PROBLEM SOLVED, maybe, probably!
There is a low pressure sensor switch in line with the compressor, so *IF* there is low pressure, won't come on and destory the compressor. Now for the down side...it appears the valve has been didlled with causing the freon to completely leak out. This is an old system, a heat pump, which requires 9.5 pounds of Freon 22 at $50 a pound !!!!
The guy came by and put a little in, if it stays, then not a waste to put more in, better to wait, just in case.
So now the question is Where to buy 9.5 pounds of Freon 22 at less than $50/pound !!
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On Jun 18, 9:21 pm, "Stormin Mormon"

I've seen it being sold on Ebay for ~$10 a pound. Everything from partial tanks to brand new ones. Of course as you pointed out, you're supposed to have an EPA certificate to screw around with it. I'd also check Craigslist for that and also guys who will do it cheaply. Of course how good, honest, etc they are is a crap shoot.
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wrote:

.
Yes, saw the eBay. But I don't do a lot there and didn't understand why they say 26 days left etc.
I hoped someone has had experience with someone and would recommend buying from them.
I need to buy one of those 30 pound tanks [looks EXACTLY like the green tank the guy brought out with him] just in case any of the other systems leaks. or this one again.
I don't mind having a certified buy come out and put in the stuff, check proper etc. that only costs $50-60 and after all that is a trip plus an hour here. It's just the getting ripped off for $500 on ONE single charge vs. getting 3 charges for $300. I would not have minded cost plus 10%, but 5 times is insulting.
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...
I've done 100+ Ebay transactions and overall, I'm very satisfied and have saved a LOT of money. I had one bad experience and that was 10+ years ago. When it was all over, I wound up short about $40.
The 26 days left is how long until that listing expires. On Ebay you can either put something up as an auction or a buy it now. With the auction, whoever has the highest bid when it ends, wins it, provided the reserve price, if any, has been exceeded.
Most important thing to look at is their feedback. For anything where it's more than $20 or so, you want to make sure they have a high feedback rating, ie 98 or 99%+ and that they have a reasonable number of transactions, preferably as seller, not buyer.
Ebay has buyer protection for I think up to $200. That doesn't cover shipping though. And read all the listing, re condition, warranties, returns, etc.
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Usually with listings that long, there is a 'buy it now' price where you can buy it at that price and it will be shipped to you in a couple of days.
Most people list things for about a week if it is a real 'auction' and longer if it is more of a 'sell' item.
About all the items I have bought on the 'buy it now' listing have arrived in less than a week. Usually ships the next day and from then it is up to the UPS/FEDEX or whoever to deliver.
Not always , but many times the 'buy it now' may have more than one of the items. You may see somenting like '10 left" That means there are 10 items left on the shelf and you can get from 1 to 10 of them. Also that means that you have to pay whatever the price is for each item. Such as if you want 3 of them, you pay 3 times the price shown. Depending on the item and seller, you may get a deal on the shipping. Several small items can be sent for the price of one item in some cases.
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