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A/C Evaporator leaks at firewall.


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I can't figure out why my evaporator is leaking down the fire wall. The drain is releasing water just fine, but when driving, i can  hear water sloshing in the evaporator area. Because my MH is so old (2002) I hate to try to begin dismantling it for fear I will only make it worse and not be able to find parts to fix it.  I attached a couple of pictures to hopefully get some ideas on what I should do about it,  if anything.   I want to see what I should do about the evaporator or should I just leave it alone.  So far, it hasn't leaked inside the coach.  I don't know what that silver valve/sensor is for and what it does.  It's pretty rusty and I don't dare fiddle with any of that stuff  until I can find a replacement parts.  Suggestions for replacement parts would be helpful as well.  The manufacture was in Ft Worth TX, but they are long out of business.

FYI.  I kept losing Freon and didn't know where the leak was until I look in the back by the motor. I found it to be wet back there at the fitting.  The nut  was loose at the condenser. It was a slow leak which caused the AC to crap out on a short distance trip. I was able to fix that.  So, be sure to check and tighten your fittings.

Also, unrelated, I am finding so many screws and things getting lose and just to let you know, it's a good time go over your MH and tighten things up.  I'll take a picture and post the kind of things I'm finding later.

 

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There should be a hose hanging down from the evaporator area. You say it is draining good but obviously not. The hose may be partially plugged, on mine there is some sort of a plastic nsert that was plugged at the end of the hose. You may want to clean the hose with a piece of wire. That "silver valve" is a vacuum actuator that opens air duct door, should close it for Max Cool setting.

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Thanks Ivan for the input.

Oh, you must be talking about the the $125 hose the repair technician put in last year to fix this leak and said it was repaired. I went ahead and stuck a thick ty-wrap about 6-8"s and it seemed to be free and clear. I attached a couple pics so you can see what it look like.  Notice how rusted the screws are. It's been doing this for a long time. I would like to replace those filters as well.  Any suggestions on the material to use?

That expensive hose does have a decent amount of drip coming out of it. As I said, I took the hose off and stuck a ty-wrap in there to clean it out.  I'd rather take it apart though. Would it be a smart thing to do?  Maybe the gaskets just wore out. I hate to try anything like that unless I know where to buy a replacement. I don't know what is inside of the evaporator.

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Jim, that sure looks like a project. Ours is a totally different configuration, all the hvac system up front, with exception of the accumulator/drier is behind the firewall and I would have to remove the whole dash to get to it. Already had to replace an expansion valve once but did not go inside the actual box. Seems like you might have better acces to remove the plastic housing but rusty sheet metal screws are no fun, soak them good first. I think you have no choice unless you can reach in through the duct door and feel the drain hole - it should open when you push on it but looks kinda rusty. I would suspect floating debree blocking the hole, since you hear the water sloshing around but still is dripping through the hose. I don't really know if there is a filter, ours looks just like a foam seal on the outside of the flap.

And I would not expect anything but the evaporator and heater core behind the cover, fan on the inside portion of the box and couple more duct doors.  Seem the door is opening in a way that you may not be able to reach in enough but an inspection camera might work to get an idea what's happening in there.

Edited by Ivan K
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Jim ,  You can remove the plastic cover .  I removed mine some yrs back when we had our Endeavor .

There are quite a few screws around  the perimeter some are hard to reach .   A 1/4 ratchett and extension

may come in handy .

Removal should allow you to see and clean  the insides and drain  .

You should not have water sloshing around  in there .  I imagine that could allow the air to feel moist  & damp and 

moisture is what you are trying to get rid of .  Dry cold air will feel much better .

My Endeavor generator did not pull out so I had to stick one leg in the gen opening  in order to reach some screws  .

I was younger then , don't know if  I would want to do it now .

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Thanks for all the comments. I'm going to soak the screws for a couple of days. I will keep you posted on the results. I'm sure someone else will have the same questions down the line dealing with older coaches like mine.

Jim

02 Cayman

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Guest Tim503

I took my unit out on a 98 but I had some other issues. Do you really want it to work? Does it work good otherwise? Remember the cooling lines come up from the engine. My fan was obnoxiously loud.These are most likely Ford units as they used Ford lights on mine. It is probably full of dust and dirt and spray it out. They are made to deal with water as that is what an AC box does is take out water from the air. Maybe find them at the junk shop in Kentucky. Wait till you remove screws on the rest of the Motorhome as most of them will be rusted and deteriorating from the awnings to the roof screws. Get one size larger and stainless.

Not sure about your unit but these were operated with the vacuum system coming off the motor in a Ford but they put in a pump with a round black globe for holding the vacuum so the heater controls can control the air control doors in this unit. That picture is a vacuum actuated control like a solenoid. The pump and round globe should be in the middle hanging on the firewall. You might want to see if all the different settings on the dash control unit make the vacuum sound and are moving properly. Could have pump problems and leaking hoses. Those two slots on the bottom of the unit are for outside air which is the opposite of inside with recirculating air with the black grate..

Edited by Tim503
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Jim,

Sounds similar to a problem I had with an 02 Diplomat. Air door letting warm air in the air box causing excessive condensation to gather in the box. Running the dash A/C on max A/C let the air door fully close and reduce the amount of condensation to a level that the drain hose could handle. Solution was to always run the dash A/C on Max A/C.

 

Bill B 07 Dynasty

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Out of curiosity, did anybody replace/remount that receiver/dryer? I've never seen one mounted horizontally like that. Seems like it'd have to be half full before it'd flow any liquid out of the pickup tube. Image attached for detail.

Also, there's a pressure switch attached to the top of it that doesn't seem to be connected to anything. I presume that's a binary switch which has been jumpered. It's responsible for preventing the system from starting if you lose your refrigerant charge, and kicking the compressor off if the pressure gets too high.

image.png

Edited by trailmug
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Hi Jim,

 

The "silver thing" is a vacuum motor to open/close vent doors. They are readily available.

I had the same leakage problem a couple of years ago that was a bear to fix. The condensation was running under the dash onto the interior rug. I tried several things and eventually fixed it by:

(1) Sealing with silicone under the AC unit where the firewall meets the rug flooring.

 (2) Installing  a sheet of thin double foil backed foam insulation onto the back inside of the whole metal box of the AC to prevent the condensation from sliding down the metal into the coach.

(3) Extending the condensation drain hose from the bottom of the AC well below the floor to make sure the condensation would not blow back while driving. 

Hope this helps.

Bob Dinsmore 2000 Diplomat

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Jim, I have my 98 Diplomat dash AC (outside the firewall) pulled apart right now. Mine looks very similar to yours except for the drier location. I had to remove the headlight assembly to get access to the cover in your photo. Mine has a heater core leak, it is at the radiator shop getting repaired. My dash A/C has not worked since aI purchased the coach 2 years ago. I pressurized the A/C evaporator to check it for leaks (it passed, yay!) before I reassemble and reinstall. 

Here are my observations, the cover is only sealed with what looks like weather stripping, mine was completely broken down and crumbly, it would not effectively keep fluids in. So, I suspect the sounds you are hearing are coming from another source (as you said, the drain tube is draining fluid).

You are right to be cautious about removing the plastic 'cover'.  Mine was very delicate and it holds the evaporator/heater core. However, it came out ok, and I didn't cause any new damage. To repair the cover if you do cause damage just get some fiberglass cloth and epoxy resin(I wouldn't advise using minute epoxy!). scuff the plastic, mix the epoxy, wet the fiberglass cloth and stick to the damaged area. Once hardened, you can drill holes that you covered over. The bottom line is it is really not a bad process to repair the plastic.

The rest of the parts are pretty robust, as long as you maintain good practices (finesse not force) you'll be fine.

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I have another update on the evaporator unit. I decided to remove  it and just drop it back a little bit so I could see what was going on.  I got it loose okay but I think something is holding it from the inside.   Looking at the inside, looks like way more work than I want to do.  I don't want to make this a project any bigger than it already is.  Moving hoses and things only intensify the risk of doing more damage then I need or want to.

I attached a couple pics so you can see I what I am seeing.  It appears the gasket or whatever seal they used had completely disintegrated. I slid my fingers where the gasket should be and it's feels like sand particles.  That is  why it's leaking and not making it to the drain hose. 

So, if anyone knows what is holding the unit from coming away from the firewall from the inside, I would appreciate it.  I only have about an inch all the way around it.  I could probably get a Dremmel brush in there to remove the most of the old gasket.  It would be a lot easier if I could detach from the inside. But that looks like more work than I want. Unless someone knows an easy way to do that, otherwise, I will probably work on it in tight quarters.

If I was able to accomplish this and get it somewhat clean, what type of sealant should I use?  I might be able to use "form a gasket" or maybe just a good bead of clear sealant caulk.  Suggestions?

Jim

02 Cayman

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I was hoping someone would know what might be attached to the evaporator and heater coil on the inside of the firewall. I got it to come out about an inch, but I'm not going to force it any further.  It seems like something is holding it from coming all the away from the firewall.  If you do know, maybe you could tell me how to detach what is holding it from the inside. I getting real close to putting it back together and letting it leak. Sometimes it's better to leave well enough alone. Thanks for the help in advance.

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I've been disengaged for the week, was putting a bamboo floor throughout the coach. Here are the pictures of mine disassembled getting ready to go back in... again, this is in a 1998 Monaco Dynasty, not the exact same model as yours. Hope it helps.

By the way, the brass fittings on the AC core are my pressure testing fittings, not part of the installation. The AC contained no gas before I disassembled the system, hasn't been functional for years. I hope to get it working over the winter. I took it apart to get a coolant leak fixed in the heater core.

 

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Edited by Eddy B
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Thanks Eddy for the pics.  Looks just like mine. 

So, I have mine loose, I haven't disconnected any of the A/C or Heater hoses.  I have everything loose and was hoping to pull it back about another 2-3 inches.  I hate to evacuate the AC because I just found the leak, repaired it and charged it. Works great.   I don't want to disturb any of the heater hoses because you know how that will go.   I'm trying to leave the connections in tack.   I have removed all of the attaching hardware so all of the lines are free to pull out 4 to 5 inches without disturbing any fittings or hoses.

Just a couple more questions. Does the cover come off of the two coils shown in the pic or does it come out in one piece with the two coils.  FYI...It's been over 100 degrees here in Texas, so I'm being very patient with this project.  It's supposed to cool into the 90's next week and I going to finish it then. 

Also, what did you use for the seal/sealant?   Did you use form a gasket or just some silicone?   I don't know what other stripping or sealant to use.   Suggestions?  

If I don't remove the cover completely, I think I can clean it pretty good.   I have a mini Dremel tool that will work cleaning it out using a mini 1" wire wheel.

Jim

02 Cayman

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The sealant (black tar kind of stuff) made mine all come out as one unit, then I disassembled it on the bench.  Mine had some weather stripping type sealer around the flange where the box meets the firewall (still on it in the photo). I plan to remove that and clean up all the surfaces, then replace with a higher quality weather stripping. I don't want to use a fluid type sealer (think silicone) because I don't want to fight it in the future if I ever need to get back in here.

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7 hours ago, Jim Andrews said:

 

Just a couple more questions. Does the cover come off of the two coils shown in the pic or does it come out in one piece with the two coils.  FYI...It's been over 100 degrees here in Texas, so I'm being very patient with this project.  It's supposed to cool into the 90's next week and I going to finish it then. 

Jim

02 Cayman

 Jim,   I live in North Tx too and you are right it is unbearably  hot  , 105 here in east Tx  this afternoon . If the covid don't kill us the heat probably will 

 It was several yrs ago when I removed the cover on a 99 Endeavor and the front of your Cayman looks so similar that I think you can  carefully work the cover loose 

 then it should  have  enough room  to ease it out .  After that I could pull the heat and cool coils out a few  inches without disconnecting the hoses .

 That might give you enough room to  accomplish the task or at least see better .

 I found a leak in the evaporator coil  , silver soldered it and  it  was still holding when we got rid of that RV .

 

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Guest Tim503

I know the truck driver in all of us want that control of heat and AC at the dash to work when we want it but why did they include fans? Because the system is inadequate for the job. I think the fan is obnoxious when it runs. I think any person should consider if it is worth it to run the  four hoses from the engine up to the dash. Are you driving it enough to keep the system going? Running the engine to charge batteries, cool the coach or heat the coach is not cost effective. Most people are not long haul drivers. They go a few hundred miles and pull over. Think about it. A better option in a rebuild would be to have those units incorporated into the house system somewhere closer to the engine I think. These units get older every year.

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  • 1 year later...

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I'm looking for the expansion valve on my 2005 Dynasty.  Can anyone point me to where I should look for this?  Attached is a picture from earlier in this posting which seems very similar to what I'm seeing.

 

thanks,

steveg 2005 DDIV

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The "hat" to the right of the yellow label with the tiny copper tube is your TXV.

As an aside, this particular photo appears to show the pressure switch (screwed onto the receiver/dryer) with no wires attached to it.

Edited by trailmug
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