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Old 07-20-2022, 10:32 AM   #1
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OTR A/C problems

Hi All,

So I am trouble shooting another Over the road (OTR) AC system problem. When I turn it on nothing happens, the fans do not turn on in any position of the AC Control Assembly, which I replaced just to make sure that was not the issue.

I did some more checking and I added 12v to the LTBLUE/WHITE and Red wire going into the AC Control Assembly (see HVAC-page2) and the fan turns on and change speeds.

So I went to the Thermostat (2 on HVAC-page1) and installed a jumper and turned on the ignition but I am not getting power to the LTBLUE/White wire. I did check the 3 fuses (7.5, 20 and 30 amps) in the Ignition fuse box drivers side forward and they all good with 12v out.

As a side note I replaced the Fan Controller with a wax valve years ago and it did not affect the OTR AC at all. Yet on HVAC-page1 (3) Relay 12v single pole/double throw relay there are input from the Fan controller, any thoughts? Where is it really located as I cannot find it to check it out. I hope to check everything out more this afternoon when I can run the RV, could not do that at 0600 in the morning. Do not want to piss off the neighbors.

Can I bypass the (1) Switch, Trinary A/C pressure to see if that could be the issue. if so how? Fun Fun

Thanks for the help.

R/--
Harry
2002 CC Allure 32' #30703




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Old 07-20-2022, 01:49 PM   #2
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All the below referenced items are from my old rig and on the front run board.

Did you check the AC Condenser Fan relay R5.

Does the AC Compressor Clutch have 12v power from its relay R8?

Fuse for wire 83 Dash AC Control

Fuse for wire 84 Condenser Relay post 30

Fuse for wires 96c and 208 AC Clutch Relay


Those areas were solutions to my Dash AC no run problems

I have no knowledge to input to your current dash ac activity.

Hope it solves easily.
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Old 07-20-2022, 05:49 PM   #3
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Update on what I found when I could turn the engine on. I am not getting the compressor clutch to engage. So the more I look at the diagrams that is not making sense. Plus I am not able to add pictures or attachments which is another issue that I will address later.

So back to the trouble shooting. I checked the 12v that comes from the ignition fuse box line 83 and at the fuse box it is good. But when i try to check for 12v on the red lines in the cab on say the AC control assembly I cannot find it. As for the Relay 12v single pole/double throw that is supposes to be on front board front bay drivers side it is missing in action as I cannot find it. So if you all have found this relay let me know where you found it. thanks

Enough for now, thanks for the help.

R/--
Harry
2002 CC Allure 32' #30703
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Old 07-20-2022, 08:04 PM   #4
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Quote:
Originally Posted by hcbradley3 View Post
Update on what I found when I could turn the engine on. I am not getting the compressor clutch to engage. So the more I look at the diagrams that is not making sense. Plus I am not able to add pictures or attachments which is another issue that I will address later.

. As for the Relay 12v single pole/double throw that is supposes to be on front board front bay drivers side it is missing in action as I cannot find it. So if you all have found this relay let me know where you found it. thanks

Enough for now, thanks for the help.

R/--
Harry
2002 CC Allure 32' #30703
I test my ac clutch with a jumper wire from the battery positive to determine if the clutch reacts to power.

The wire from the AC Clutch Relay on the front run board should show 12v at the clutch. Your AC Clutch relay could be bad. My AC Clutch relay is a 5 pole Bosch type relay. No switch externally.

My AC Clutch fuse on the front run board is in the center row of fuses that light up with the ignition switch on. If it is not lighted, you have a bad fuse. My fuse is at the bottom of the center vertical row of fuses.

Perhaps your setup is different.
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Old 07-20-2022, 08:12 PM   #5
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This wiring schematic is for a 1995 CC Magna with front and rear AC Dash ac.

Yours is likely different due to model and vintage.

It is offered just in case....
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Old 07-21-2022, 09:13 AM   #6
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Ok, this morning I managed to do a bit more trouble shooting. I was able to add the 2 wiring diagrams that shows the OTR HVAC system for a 2002 CC Allure.

The relay 12v single pole/double throw which is supposed to be on the drivers side is in fact on the passengers side of the dash, found it. I added 12v to the RED/White wire on the control panel (8 on page 1) and when I switched over the switch to A/C the AC compressor engaged like it should. So the circuitry from the switch to the compressor is working correctly.

So I am back to trouble shooting the 83 10g RED wiring from the 30 amp fuse in the Ignition fuse box image 2 to the A/C control assy image 1. When I try to follow the wire it gets lost once it goes through the floor under the dash. I added 12v to the red wire once it was disconnected from the fuse panel, that way I can test it without the RV running. So I had 13v at the fuse end of the wire but only 10v at relay #1 image 1 and at the A/C control assy. if it is a straight through wire why is it dropping voltage? This voltage at the A/C control assy is with the connector disconnected. When I connect it I loose the voltage completely. the assy is brand new from FORD.

Enough for now, thanks for the help.

R/--
Harry
2002 CC Allure 32' #30703
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Old 07-23-2022, 06:16 AM   #7
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Hi All,

Back with more updates on my trouble shooting journey. So, if you check out the wiring you will see the 12v circuit from the ignition fuse panel to the AC control assy and relay #1 seems to be a direct shot but for whatever reason i am getting a voltage drop from 13.4v to 9.3 volts. Also, I checked for a short and did not find any. I have been trying to trace the wire, but it is a nightmare of wires from behind the kick panels under the dash. So, if anyone has any ideas, please let me know?

R/--
Harry
2002 CC Allure 32' #30703
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Old 07-23-2022, 07:26 AM   #8
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Quote:
Originally Posted by hcbradley3 View Post
Hi All,

Back with more updates on my trouble shooting journey. So, if you check out the wiring you will see the 12v circuit from the ignition fuse panel to the AC control assy and relay #1 seems to be a direct shot but for whatever reason i am getting a voltage drop from 13.4v to 9.3 volts. Also, I checked for a short and did not find any. I have been trying to trace the wire, but it is a nightmare of wires from behind the kick panels under the dash. So, if anyone has any ideas, please let me know?

R/--
Harry
2002 CC Allure 32' #30703


A lower voltage reading can indicate a ground issue. - confirm ground continuity. I found a couple of connectors in the harnesses corroded, not making good ground.

A suggestion.

Brian
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Old 07-24-2022, 04:54 PM   #9
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Have you bypassed the pressure switch yet? Maybe there is not enough Freon for the switch to let the compressor start up.
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Old 07-29-2022, 11:40 AM   #10
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Hello all I am back,

Had to take a few days off to spend some time with the other half. So, I started off today disconnecting connectors that the red/white wire are going to in the diagram starting at the control assembly that way isolating the control assembly from the rest of the wiring. I also disconnected relay 1, 2, 5 and the drivers fan switch. Plus, I disconnected both of the blower motor resistors to make sure one was not bad.

So, with all of that disconnected I am still getting 80 ohms when I check it to ground. So, WTF is going on here. Why am I getting 80 ohms when I should see an open? Either I am going crazy or the wiring diagram that came with the coach is wrong. fun fun!

I checked for a ground issue and could not find any. Also, you cannot bypass the pressure switch on my unit as it is hard wired, does not have a plug. I also added 12V to the 301 16g BLK / LtBlue/White wire going to page 1 and the compressor engages like it should, so I am thinking there is no problem with the pressure switch.

R/--
Harry
2002 CC Allure 32' #30703
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Old 07-29-2022, 03:23 PM   #11
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I've found it best to perform the basis and easy diagnostic checks first. Verify if or not 12v + at compressor clutch with a multimeter. If yes - either a faulty clutch coil, ground or wide air gap. If no - check for system voltage on both electrical connectors on the binary switch. Having power on both legs will indicate sufficient freon to allow to energize the clutch.
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Old 07-30-2022, 05:54 AM   #12
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Duck Hunter,

With everything put back together I get no voltage to the trinary AC pressure switch or the compressor clutch. However if I add 12v to the 301 16g BLK / LtBlue/White wire going to the pressure switch and the compressor clutch it does engage like it should. So there is no problem in the engine compartment, pressure switch, compressor clutch or lack of Freon.

So with no power going to the back of the RV the issue has to be under the dash of the RV someplace in the mess of wiring associated with the HVAC system.

Thanks for the help.

R/--
Harry
2002 CC Allure 32' #30703
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Old 07-30-2022, 07:14 AM   #13
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Ours is different but could be similar issue.

In the front where the power distribution box is located they used huge multi-wire connectors to allow the assembly of pre-assembled parts.

You stated 12 volts at one end with 9 volts somewhere else.

This is usually caused by bad connection.

To find them is difficult but here are some "tricks"

1. Extended leads, get a cheap roll of single conductor wire, size does not matter, small is fine, just needs to be long enough to get to other end of measurement.
2. Some "clip leads" these are usually short wires with alligator clips on both ends, makes for easy hands free connections.
3. Sewing needles or pins, these are used to puncture a wire to connect to the conducting wire inside.
4. roll of electrical tape

Using your wire with voltage drop.

Roll out the wire above between the 2 points of measurement.

With clip leads coect one end to the wire at one point and to point of measurement, be careful to not let anything touch ground, wrap with tape if needed.

At other end with your voltmeter, attach the leads to the wire above and other point of measurement.

If the measurements before were 12 and 9 volts, you should read 3 volts.

You are measuring the voltage drop of the wire.

Activate switches, it should change.

Look for connectors with that wire.

If you find one do NOT unplug it.

Insert a needle or pin into the wire on both sides of the connector.

Check for volts to ground both sides then check for volts between them.

Should always be zero volts between them.

If you measure volts between them then use clip leads to attach meter to pins, now wiggle connector to see if voltage changes.

Unplug, inspect and repair.

Done this for many years, ours had a few weak connections in the front that we had to find.

In our work life we have found many atx fuse holders that do not grip the fuse well and do this.
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Old 08-16-2022, 04:20 PM   #14
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Afternoon All,

So, I got the OTR AC working finally. I had to replace the main power line from the fuse panel to the wiring behind the storage compartment passenger side, 83 on the wiring diagram. Also found a bad 4 position blower switch on the passenger side AC controls. So, I have 2 more questions now:

1 - does anyone know the part number for the 4 position blower switch? nothing is written on the switch that can be checked.

2 - I do not get the right venting of air now because I think I got my 5 vacuum lines mixed up. When I should have max AC I get defrost vents.

So here are how my lines are installed starting top left to right. Yellow, black and red. bottom left to right is white, blank and green. This is viewed from the floor looking up at the back of the main AC control assy.

Thanks again for all of the help.
R/--
Harry
2002 CC Allure 32' #30703
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