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386kustoms · 02-03-2011, 07:16 PM

i asked a question earlier but i think im confusing what im looking for lol so ill start a new thread. i dont have the 24 volts going to my thermostat. i have a 66 safari. honeywell thermostat. anyway im trying to figure out wher ethe 24 v wire comes from exactly so i cna figure out why im not getting the needed volts to turn the ac on. all fuses look good and breakers look good. any ideas where to start or where i can find the wire so that i can test it at the sorce to see if maybe there is a break in the wire somewhere?

richinny · 02-03-2011, 08:14 PM

i think you might be looking for 12 volts. i've read that folks have use 24v thermostats in their units with good results.

i again think that the thermostat is a switch and is powered from the ac.

can you post the year and model of the unit in question for the experts? :-)

Jammer · 02-03-2011, 08:58 PM

I believe that on the older (1960s) units the wire comes from the air conditioner, where a 24vac transformer is located.

Newer units that have a single thermostat for both the furnace and the air conditioner usually use 12 volts.

TG Twinkie · 02-03-2011, 10:37 PM

You will not have 24 volts at the thermostat. The thermostat is in what is called the switch leg. In the air conditioner unit there is a 24 volt transformer, which puts out 24 volts AC (alternating current). One side of the transformer is connected to the thermostat and the other side of the transformer is connected to the common side of the circuitry within the air conditioner. Don't confuse this with the ground/common side of the DC circuits in your trailer.
If you want to check to see if there is 24 volts at the thermostat; the contacts in the thermostat must be open. Thermostat turned all the way down. When you read across the two wires you may get 24 volts, I'm not sure because there could be other devices in the circuit. But try it.
Do you have a drawing of the circuitry? Usually a label inside one of the covers has a drawing.
What brand of air conditioner is it?

TG Twinkie · 02-03-2011, 11:15 PM

Here is a drawing of a control circuit. Don't know if is the same as yours.
In the middle of the drawing down at the bottom you will see the transformer. In series with the transformer there is a cooling coil relay (see terminals 4 & 5). It doesn't appear that there is anything else in the circuit. So my thougt of reading the 24 volts at the thermostat will work. You have to have your meter on AC (alternating current) to be able to read it. Make sure the thermostat is turned all the way down.
This cooling coil relay closes a set of contacts (see terminals 3 & 6) labeled "C1-cooling coil contacts); which in turn causes the start relay (terminals 1 & 2 & 5)to pick up. The first thing that happens is the motor is powered thru the start capacitor; when it reaches a predetermined speed it switches to the run mode and the start capacitor is out of the circuit and the run capacitor is in.
The thermostats contacts pick up and drop out the cooling coil relay; which controls the compressor motor for making cold air.
Does your unit make any noise at all?
I see a switch on the drawing that is not labeled just to the left of where it says "fan cap" above the three position speed control switch. Are you sure you have all of the switches on? With out that switch on, nothing will work.
There are two different control circuits on this drawing but they are basically the same function.

386kustoms · 02-04-2011, 10:52 AM

nothing comes on at all. no fan no clicks no noise. its like there is no power getting to the system. and the wires run through the walls that si why im just trying to figure out and trace the wires.

TG Twinkie · 02-04-2011, 11:44 AM

Can you post a photo or two? Have you taken any covers off of the unit to see if you even have 120 volt AC power to it?
If you can take the cover off of the inside and shoot some pics maybe I can help more.

386kustoms · 02-04-2011, 02:10 PM

i will try to get pics this weekend i dont have a working camera. i did take teh shroud off and i found the 120 volt wire. i traced it to the low and high speed fan relays. it has the 120v there. but nothing after them. is the fan motors 120v as well? i tried jumping the fan and still got nothing. i mean this unit is very old and has some rust inside and im sure i will need a new unit. but b4 i go and spend 600 bucks i just want to be sure it isnt somethign simple

garry · 02-04-2011, 04:04 PM

Fan runs on 120VAC and should come on in the fan position without the thermostat so you have other problems.

Could be the start capacitor , bad relay, bad fan motor or ???

But the fan should run even if the AC compressor will not kicking in.

TG Twinkie · 02-04-2011, 07:02 PM

I agree with Garry. Relay, capacitor, bad fan motor. Can you tell if the fan relay picks up when you try to start the fan only? Do the wire connections look corroded? If so clean them up and give it a try. Do you have access to the fan blade where you could give it a spin to see if it's free? If so turn on the fan and try spinning the fan blade by hand to see if it will run. if it runs it is a bad capacitor.

386kustoms · 02-05-2011, 06:43 AM

the fan spins free by hand. there are 4 wires going to it red white blue and ? ( i forgot) lol. anyway looking at the diagram in the unit it looks like the red wire would be the power wire for the fan. so i unpluged the red wire from the relay and put 120v right to that and still no noise and it didnt turn the fan motor case itself looks kinda surface rusty but the internals inside the motor still look decent ( the red colored coper wires) why are there 4 wires going to the fan? and the diagram really dosent show what wires are what exept the white wire is common. i take it common is like ground or should common have voltage to it at all times to?

TG Twinkie · 02-05-2011, 08:40 AM

There are 4 wires going to the motor because it is multiple speeds. When you look at the schematic I sent you can see there is a red (low speed), blue (medium speed), black (high speed) and white.
How do you change speeds of the fan? Is there a series of push buttons or is it a rotary switch?
What are the wires that come from the motor connected to? A terminal strip or what. Are they the connectors that slide over a flat terminal (commonly called spade connectors)?
I still think you have a power problem. It seems odd to me that all three speeds of the fan motor would not work. Either the capacitor is out or you have a bad connection some where.
When you say you are putting 120 volts to it. Exactly how are you doing that?

garry · 02-05-2011, 11:05 AM

On both models the fan should come on as soon as the switch is made through the on/off 4 position (gang) switch.

Position 1 provides power to the thermostat position and 2,3,4 control fan speed.

The thermostat controls the relays on the compressor side.

The only difference in the 2 diagrams is most likely the size of the compressor and the neutral connection.

You have to have 4 conditions to make the fan come on.

1. 120VAC into the switch at "H" black wire
2. A good switch.
3. A good fan motor start capacitor.
4. A good neutral connection.
On the left diagram model 25-12 the neutral connection comes in from a fused disconnect through the switch terminal G white wire.

On the model 25-14 apparently the neutral comes in terminal G is not fused and does not come in through the switch.

Your comment you pulled a red wire from the relay and applied 120VAC?? There is no red wire from a relay to the fan motor.
A red wire from the switch through an unknown connector (little round circles in the wire diagram denote a connector) between the switch and the motor.

TG Twinkiy can guide you through the troubleshooting but you have to be his eyes that's why you have to be pretty specific about what you have done.

BE VERY CAREFUL applying 120VAC to unknown places will get you into trouble and possibility of injury.

TG Twinkie · 02-05-2011, 11:32 AM

I an earlier post you stated that you read 120 volts. Where did you have you meter leads when you read the 120 volts. If you were touching the power lead with one probe of the meter and the skin of the trailer with the other, you would get a false reading. The neutral in your trailer is not grounded (at least it shouldn't be). On the drawing I sent it shows a fused disconnect, but it's probably a circuit breaker in the trailer power panel.
If you are reading voltage by touching one lead of the meter to the chassis (skin), then you may have an open neutral.
Be sure to check the voltage on the black and white wires coming into the unit.
On the left drawing there is a terminal strip.
Just to the left of the Fan motor. Do you see anything like that in your unit? If so make sure the connections are clean and tight. On that terminal strip there are 3 white wires connected to it, one on the bottom of the terminal strip and 2 on the top. There would need to be either a jumper wire between the 2 on the top or a metal buss bar, because all 3 of these wires need to be connected. Again check for corrosion etc.

386kustoms · 02-05-2011, 12:10 PM

its raining outside right now so i cant do much. yes i grounded it out by using the trailer, next time i climb up there i will use the green wire as the ground. let me take some pictures of the unit and that may be of help to you helping me out.

TG Twinkie · 02-05-2011, 12:49 PM

No! Don't use the green wire. Read between the black and the white wire to see if you have power.

386kustoms · 02-06-2011, 08:43 AM

camera will be here soon so i will take pictures. i did climb back up and read between black and white wires. i probed white wire with the ground on the meter and the black wire i used pos on meter. it read about 125 volts. traced the black wire to the relay and still read the 125 volts. from the lo relay there is a red wire that runs to the fan and that only read abotu 5 volts. same with the high relay, the wire that ran from that to a compacitor then to the fan only read 5 volts. and finaly there is a wire ( brown i belive) that runs from the other side of the capacitor to the fan and that was reading very low volts. also that single wire that runs from the cap to the fan was pinched really bad and may be broken inside the sleeve. also while i was up there i tested the g1 g2 wires and they read 5 volts as well. my main concern first off is to see if i can get the fan running. i relize the white is ground for the fan, but out of the red, blue, and brown wires wich wire needs the 115 volts to run the fan?

386kustoms · 02-06-2011, 09:51 AM

pics are here. i cant upload them on this site for some odd reason

airstream pictures by 386kustoms - Photobucket

TG Twinkie · 02-06-2011, 02:30 PM

First thing to do is see if you have 24 volts AC coming out of the transformer. If you can trace the red and yellow wires coming out of the transformer to where you can put your meter on a connection. With power on you should see about 26 volts AC. According to the drawing the yellow wire is spliced to a red wire and a black wire. The black wire goes to the Low Speed relay. You might be able to read between the red wire on the terminal strip and the black wire on the relay to see if you have 24 volts AC there.
In looking at the photo; I don't see any wires coming off of the terminal strip with the G1 and G2 terminals. Only the wires that look like they go into the control box. Is there more that one wire connected to the terminal G1?
Where is the thermostat located? On the unit?
If you have the 24 volts, you could try and jumper between "R"terminal and "G2"terminal to see if the low speed fan relay will pick up.
I'll wait to hear from you before we move on.
Try to answer each of my questions as best you can.

386kustoms · 02-06-2011, 04:12 PM

i will climb back up there tomorow if i get home in time while light out. there are more wires coming from g1 and 2 they are just under the other wires. hard to see in the pic. i will check for 26 v at the transformer. you say turn the unit on correct? will both wires coming from transformer have 26v? the thermostat is located in the trailer near the bathroom, i tried jumping the wires the other day with no luck. i will get back to you with the result of seeing how many volts are coming from transformer