I have a 1994 RB Club Wagon passenger van with rear a/c, however, the rear a/c isn't functioning properly. I was hoping to get some insight as far as where or how to start diagnosing my problem. I would love to get the rear a/c working but just need to find out what it needs.

The front a/c works like a champ. I can switch the rear a/c on from the front and I can hear the a/c in the back running. When I walk back to the back of the van, I don't feel cold air coming out of the vents. I think when I first bought the van, I remember feeling warm air moving when I put my hand down by the rear a/c unit, but I don't remember for sure. If that helps narrow it down I can see if I can confirm it.

That's what I know, please let me know where to start, so I can figure out what I need to do to fix it.

Thank you.

 

hook a manifold gauge up to the back there should be the connections under the van near the gas tank and see if there's any r134a in it. had to do that to my 2000. also there is great info in this sticky for you

https://www.ford-trucks.com/forums/1...-controls.html

 

The only service fittings for the A/C system is up front and if the front A/C is working the system is holding pressure and the compressor seemingly working as designed. Is this a factory rear A/C system or aftermarket? Any images of the front heater control on the dashboard?

Does the air flow change from floor vents to roof vents when A/C is commanded either up front or the rear overhead control (if so equipped)? Does the blower speed vary with the fan speed control?

If the air doesn't change from floor to roof that typically means the vacuum solenoid to change from A/C to heat has failed OR it has somehow lost its vacuum signal.

Once you've answered these questions we might be able to help a bit more.

 

If the air blows out the floor vents and not the ceiling vents when you turn on the rear ac more than likely the vacuum operated motor arm broke off the blend door, very common on 92-96 vans. Unfortunately the door is obsolete from Ford. You can remove the inside plastic panel to verify the arm is no longer attached to the door. Rig it to stay always in the ac position for the summer.

 

This is the control in the dash. As far as I know it is the factory installed rear a/c.

This is the control in the rear of the van.

I messed with the control panel in the front of the van this afternoon. I realized that the rear a/c only comes on at the low and high fan settings, the fan doesn't run on the middle two settings. I tried several settings on the front control but the rear air only comes out of the floor vents and comes out warm. Also, the rear control didn't seem to have any input on the fan speed in the rear. That's not a major worry to me right now, but thought I would mention it in case it helps with anything from a diagnosis standpoint.

Any tips on what to look for from here would be greatly appreciated.

 

Front panel control, putting the **** in the first position from off allows rear fan switch to work the rear blower. The next 3 speed settings overrides the rear control. If speeds other than high don't work the resistor block has faulty resistor circuits. These are available on Rockauto. If the air blows out hot and through the floor vents then the door on the rear evaporator case is not changing position from heater core to evaporator which also changes the air flow from the floor to the ceiling vents.

 

Part #15 in this diagram is the door . Usually the plastic door breaks where the vacuum motor rod connects to it. The doors are obsolete from ford.

 

Your A/C system is indeed factory installed.

What does the front blower do as you move the speed control through its steps? The rear fan speed is or should only be affected by the front control for that blower only IF its NOT set to the "rear control" setting. Try "messing" with all the blower speed controls, setting them to front control only then to rear control and see if those functions operate properly.


You'll need to physically remove the switches or at least gain access to them for a physical inspection. They've been known to melt or at least disintegrate due age and/or constantly passing current---they're not that high quality anyway, even the factory versions. The following image shows such a situation:




As for the blend door possibly breaking---that needs to be determined by physical inspection. There will be a blue plastic line for the vacuum signal that should be present when A/C is commanded. Any parts in the rear A/C blowing housing can probably be found as I'm sure Dorman makes something. If the drawing Steve460 posted is of the 1994 years then it looks nearly exactly like the one I removed from my 2005 E350 with factory rear A/C. That being so parts will still be available.

So double check your switches and look for the vacuum signal at the rear blend door.

HTH

 

92-96 doors are different from 97 and up doors although the ford diagram is generic for all years. Google it and you can find some pictures of people that have jb welded their door rod mount . Doorman does not make a door for 92-96 evaporator cases yet.

 

I really feel like a dummy now, lol. It didn't click to me that the "rear control" meant that setting on the control **** gave control to the rear control. I was thinking that was more of a general this control **** controls the rear, as the **** above controls the front. It's so clear now, but for whatever reason that hadn't clicked in my head yet.

So, I did mess with the controls again today. To answer the question about the front blower controls, all speeds work as designed on it, no known issues with it.

The front control for the rear blower does work on the "rear control" setting and does allow the rear control to take control. The 'low' and 'high' settings do work as designed, the only one that does not activate the rear blower is the 'medium' setting.

Once you set the front control panel to "rear control" it allows the rear control panel take over, and all three settings on the rear control effect the blower motor as they should.

It looks like the only setting that isn't working is the 'medium' setting on the front control for the rear unit. From the sounds of it, it sounds like the next step for figuring out why the a/c is blowing warm air out of the floor vents would be to pull the panels in the rear of the van to gain access to the rear a/c unit? Basically I need to see if the blower motor arm is broken or if there is a problem with the vacuum that controls the arm?

Thank you all for your help this far.

 

Yes removing the inside panel is the only way to inspect the case. I ordered my van in late 93 ,94 club wagon chateau hd 460 quad captains and rear fold out bed. Over the last 26 years i have replaced the door 2 times, probably should have bought a spare. My suspicion is the foam around the door sticks to the case over the winter time from not selecting a/c, then summer comes and the first time rear a/c is selected the arm breaks off the door, the vacuum motor is extremely strong. You will need to remove the trim around your window in order to get the lower panel off. The window trim has plastic tongues that fit into metal clips with teeth, be careful when pulling on the trim and take your time pulling straight out, you will think your going to break the trim but the clip will finally let loose.

 

Another part affecting any blower speed is the resistor network Ford installs---along with the switch failures I mention the resistors can also have one or two "speeds" fail. The front resistor is located in the evaporator case, typically at the front but a bit low. Th rear blower/heater core/AC evaporator housing holds its own separate resistor.

 

I don't know if your problem got solved, but I thought I'd throw this into the mix. Mine is a bit newer than your van, but I don't think there were significant changes made.

Anyway, if your van uses vacuum controls for the HVAC, there should be a metal part attached to the plastic casing. That metal part has a rod sticking out the top and a small hose underneath. It is a diaphragm that pulls the ventilation door up. The door is supposed to be in the up position when the AC is on and the down position when you want heat. It throws AC into the ceiling vents and heat along the bottom. That vent door on mine (plastic) was broken right where it connected to the rod going to the diaphragm. I bought a new door and put it back together and everything worked as it should.

While you are there checking things, disconnect the airline to the diaphragm and suck on the end leading to the diaphragm. You should see the rod move downward.

You might also have the ubiquitous problem of a failed vacuum tank (also plastic) and/or check valve. Typical symptoms are air blowing out the defrost and to the floor when accelerating, and out the face vents in the dash when idling. There are a number of threads on fixing this. I ran new hose into the cab and installed a replacement vacuum tank and check valve under the dash on the passenger side. Total cost was around $70 or less, including the canister ($40), some 5/16" hose (I think I got 3 feet, which was way more than enough), the check valve ($12-15), and some hose barbs.

 

Yippee's situation doesn't sound like this too often failure is part of his situation but its a good point---I've used Ford parts when fixing at least three different E-Series vans, all 1997 and later. I've found both parts very competitively priced through my Ford dealer but Amazon sells them too:





I did create a write up on replacing those parts but inside the cabin rather than fumbling around under the hood. Should any one not using the search function want photos of how I did this I'm glad to share.

HTH

 

I am having an issue with slightly different symptoms but I am guessing the same cause.
2012 E350 15 pass 5.4 flex fuel.
Rear air come on blows out cold but switches to floor heat at random times and also when the front air switches to defrost.
I have pulled the trim panels and blower motor ( from rear) and the door is not broken - that is when I started to try to pattern the behavior - some times the rear switches when the front has not...

I am going to put in new check valve and resv ( since i and have the acceleration related switch to def up front)and see if that stop the erroneous operation from the rear
thanks for your your path finding work - I appreciate it!