A/C not starting up - Help needed

Need a little help over here......
I have a condo.... with a two part Bryant A/C system. One part is the compressor and squirrel cage blower vented through a brick wall to the outside. The compressor pumps freon to a ceiling unit which contains blower and distributes the cooled air into ductwork.
A/C system is not turning on..... I'm not getting 25 vac ac to the wall unit. Backtracking the wire...it seems that the low voltage is generated by a transformer and relay in the ceiling unit. Line Voltage is present on both units, but a measurement on what should be the low voltage circuit does not show any voltage.
So, here's why help is so desperately needed. We called BGE Home two weeks ago, they scheduled a technician for last Monday afternoon. I lose 1/2 day from work....BGEHome technician walks in and says.... you need to remove the ceiling panel before I can work on the system. He writes a bill for $85.00 and leaves. Tuesday I arrange people to come in and remove the ceiling panel to the ceiling a/c. Not a difficult job. I place a service call...BGE home says....we'll have a technician out on Friday. Friday comes, I have the ceiling company standing by, ready to replace the a/c ceiling panel. BGE Home technician calls and leaves this message, "I won't be out there today. Bye"....
So the ceiling people leave...2 people at 75.00 per hour for 4 hours waiting for the BGE Home people. Irate we call BGE... They promise PROMISE AND PROMISE....WE WILL have a technician out there on Saturday. Again...we wait. A technician walks in, says "Oh, I don't work on these...I'm only an instructor" and walks back out the door. Wait, we say...'who's going to fix this" and he says " Oh, I'll call the regular repair rep...he'll be out tonight. So I call BGE Home and speak to the "duty manager" who is your typical lousy customer service dead end guy.... the one who is supposed to get the irate calls and doesn't give a rat's ass about customer service. He promises to send a 'senior technician' out on Monday. Again someone has to be home from 12 to 4. I ask him if he see's ANYTHING wrong with the whole scenario. He says "Oh, I'm not a technician". This is BGE Home in Washington D.C. a somewhat major city.
BGE Home has ONE telephone number for the entire operation.... so corporate mid-level management is well protected from their customer base.... sound familiar ???
Any help is appreciated...... if you live in Washington, D.C. and have a good service company please let me know. Secondly, is there someplace online where I can get a good service manual for the unit...provided I have a unit number.... and Thirdly what's a good logistics source for Bryant air conditioners ???
What signals should I be looking for in the low voltage circuit....there are 5 legs on the relay which is mounted onto a step down transformer.....probably 2 line input, 2 output and there is a 5th wire in the center of the relay.
Thanking you in advance !!!
Peter
PS... To the doom sayers... it's okay... I had years of experience of troubleshooting computer and aviation electronics.... so I won't fry, I won't try to recharge the high pressure side of the compressor and I promise to put all the screws back in the ceiling panel when finished. Did I miss anything ??? I shouldn't have to be doing this myself.....
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Peter wrote:

<SNIP>
Argh! I feel for you.
First, there should be a controls diagram *somewhere*, probably at the ceiling unit.
Measure if there is 24V right at the xfmr terminals. Work from there.
Jim ex-DC'er
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There is a control diagram on one of the squirrel cage housings...trouble is it is covered in dirt and all attempts to clean the dirt off just obliterates the diagram. This is curious as the rest of the housing looks very clean and the unit itself looks very clean. Just the diagram seems to be collecting dirt.
No 24V (no low voltage) coming off the terminals....... . Would it do any good to remove the relay and transformer to ohm them out ??? Is there anyway to obtain a replacement part ???
I'm also thinking of trying to get a 24vac source to energize and test the rest of the circuitry, using one of the old telephone step down transformers....low voltage low current... any drawbacks to this method ??? (other than turning on line voltage to test).
I'll be back there tomorrow....too hot to spend the night (condo's suck up heat and the windows aren't the best in the world). Any other answers or thoughts are appreciated !!

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Peter wrote:

See if there is 120V on the xfmr primary. If there is, Ohm out the primary. The relay shouldn't be needed just to get 24V from the xfmr. If no 120V on primary, work back.
A tel. xfmr won't have enough voltage. Big Box store might have HVAC basic components like this.
Jim

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Radio Shack or Home Cheepo might have a suitable transformer.
--

Christopher A. Young
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No 24V (no low voltage) coming off the terminals....... . Would it do any good to remove the relay and transformer to ohm them out ??? Is there anyway to obtain a replacement part ??? CY: Better to see if the Xformer is getting 110 VAC power.
I'm also thinking of trying to get a 24vac source to energize and test the rest of the circuitry, using one of the old telephone step down transformers....low voltage low current... any drawbacks to this method ??? (other than turning on line voltage to test). CY: You'd need to take out the old Xformer while doing this. But first, check to see if the 110 volt system is getting power. Very likely the system doesnt have line power.
I'll be back there tomorrow....too hot to spend the night (condo's suck up heat and the windows aren't the best in the world). Any other answers or thoughts are appreciated !! CY: Make sure the electrical line power is on. Probably 110 VAC for the indoors, and 220 VAC for outdoors.
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Absolutely. I'm biased against this part because it's the one that failed 6 weeks after I moved in, when I had 3 people visiting from out of town, to see my new home. A very hot July 4 weekned. (That failed Saturday at noon. The water failed Saturday night, and the rest of the electricity failed on Sunday. It was incredible. The AC hasn't failed since, and I've never had a month when more than one of the other two have failed since.)
I went to a HVAC supplier and the whole board was about 200 dollars. They didn't sell the built-in xformer separately. But after I whined a bit about spending all that money, they sold me just a transformer for about 20. Too big to fit into the space on the circuit board, so I mounted it elsewhere in the furnace. 23 years later, working fine.
But like they say, you don't have to go to an HVAC supply company for a standard part like this.
I know there are amp and watt ratings but there weren't on the one I was holding, and I just accepted what they gave me and figured it's bound to be good electrically, because physically it was bigger than the one it replaced. All other things being equal, the physical dimensions ARE proportional to the electrical ratings.

I think I have two of those in sequence that I used in 1968 to play games on my fraternity brothers. Substantially smaller than the one that came with the furnace and even more than the one they gave me to replace it.

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--------------------------------------------------------------------------------------------------------
IF you have 120 on the input of the xformer and no 24 on the secondary, the xformer is shot, or maybe the secondary is fused?
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OK, line at a time. Look for my inserted text.
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