I'm a newbie to the RV world and would love some help dealing with a problem with the Evans Tempcon dash AC. The coach is a 2001 Monaco Knight on a Roadmaster chassis. I bought this RV knowing the dash air didn't work right but was told it hasn't been used for almost a year and most likely just needed charging. We loved so much about it (Diesel pusher Allison trans, looks new inside, outside and awnings, Aluminum roof - not the rubber cover stuff, everything else worked great just 30,000 miles) we bought it anyway. I took it to TAG to get the AC fixed and the trouble started... After being jerked around for over a month, the parts had arrived to fix it. Now I am being told they can't get it disassembled without destroying the plastic cover. The cover is already cracked in a couple of spots and has a "RV200527" part number on it. That cover has several bolts around it that they've removed, but it is still won't slide out. Compounding the problem is the fact they can't locate a replacement cover. I see that the cover also has some rivets in it, but that could just be to a frame. And to top it off, these jack-wagons have put a tear in the dash that was in perfect condition - just like the rest of the RV. When I asked them about it, the technician said he didn't do it. So now I'm really ticked off and want to just go pick it up and never take anything to them again. But I need to get it fixed, they have the part, and if I leave the chances of getting them to fix the damage they did to the dash drop from slim to none. Any help (assembly diagram, advice, anger management tips (lol)...) would be greatly appreciated.

MSU Dog Hauler wrote:I'm a newbie to the RV world and would love some help dealing with a problem with the Evans Tempcon dash AC. The coach is a 2001 Monaco Knight on a Roadmaster chassis. I bought this RV knowing the dash air didn't work right but was told it hasn't been used for almost a year and most likely just needed charging. We loved so much about it (Diesel pusher Allison trans, looks new inside, outside and awnings, Aluminum roof - not the rubber cover stuff, everything else worked great just 30,000 miles) we bought it anyway. I took it to TAG to get the AC fixed and the trouble started... After being jerked around for over a month, the parts had arrived to fix it. Now I am being told they can't get it disassembled without destroying the plastic cover. The cover is already cracked in a couple of spots and has a "RV200527" part number on it. That cover has several bolts around it that they've removed, but it is still won't slide out. Compounding the problem is the fact they can't locate a replacement cover. I see that the cover also has some rivets in it, but that could just be to a frame. And to top it off, these jack-wagons have put a tear in the dash that was in perfect condition - just like the rest of the RV. When I asked them about it, the technician said he didn't do it. So now I'm really ticked off and want to just go pick it up and never take anything to them again. But I need to get it fixed, they have the part, and if I leave the chances of getting them to fix the damage they did to the dash drop from slim to none. Any help (assembly diagram, advice, anger management tips (lol)...) would be greatly appreciated.A 17yr. old dash air will always be a headache. Forget about it and run the gen. plus house air when traveling.

If they can't get it off without damaging it that's not thier fault. Of course, the tear in the dash is though.

That vintage had an issue with bad mixing valves. Check under the hood at the hoses coming from the compressor. What the valve would do is stick part way open so you'd get warm air at best. If you stopped the flow of warm fluid the AC part worked well. If this is what it's doing you could simply put in a bypass valve. If that's not it, sorry and good luck!

First off, the replacement part can most likely be purchased from Northwest RV Supply in Coburg. They bought all Monaco's stuff when they closed up shop. Maybe negotiate the price of the part for the tear in the dash. Worth a try. Even a discount would make it a win/win. Then take it to someone who knows what they're doing. A call to REV in Coburg could most likely provide you with guidance in it's removal. They still have the Monaco techs on staff...Also, a lot of those part numbers are Monaco specific even tho they're made by someone else...DennisNW RV 866-678-7467

I had all that apart a few yrs ago when we had our Endeavor , it is the same in that area as yours . They probably don't have all the bolts / nuts removed yet and of course it's going to be stuck some . The tech is obviously angry about having to work on it , it's not the normal auto air cond . It's not real easy to work in there but if a 70 yr old could do it I'm sure they can too . What is wrong with it that they need to remove that cover ?? Have them find a good vinyl repair man , he can repair it so you can not find the repair I have had mine repaired and it was perfect

Evans Dash Air Nightmare | Good Sam Community

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MSU_Dog_Hauler
Explorer
Aug 09, 2019
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UPDATE!
I ended up pulling the RV from TAG. I couldn't take getting jerked around by them any longer. I told them I had plans to go somewhere in it and needed to pick it up at the close of business on a Friday. When I showed up 15 minutes till close they had the nose piece off the RV, AC hoses dangling inside and nobody working on it. I almost lost my mind! I pulled my wrenches out of the RV and started putting it back together myself. They had someone start helping me and tried to get me to buy the $700 service part they had purchased. But when I looked at it I knew there was no way it would have fit my system. It was about 2x the size of the space I knew it had to fit. I told them I would think about it and drove off. I then had an independent diesel mechanic experienced in AC work look into it. Since TAG had opened the system, he had to replace some small components, a few o-rings and inspected everything so he could charge the system and look for a leak. He found no leak, but did find that the belt for the AC compressor was missing! He replaced the belt and air has worked like a charm since. I taped up the cracks in the plastic housing with gorilla tape and have had no issues whatsoever. (Knocking very hard on every piece of wood within reach...) I waited several weeks and then stopped back by TAG after I was sure there were no other issues or leaks. How can I say this nicely???? Well I wanted to be sure they had a full understanding of the situation and my level of dissatisfaction. I think they do. I'm actually thinking of taking them to small claims court to recover what they charged me.
dougrainer
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Aug 09, 2019
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oldave wrote:
Not sure what you mean by vacuum motor but there is no motor in the
black box . You are exactly correct , 12v operates an air valve ,
air is the passed thru the venturi to create vacuum as needed .
When done right the venturi is a terrific little devise but I suppose
the 12v pumps became so cheap and good where the black box probably
got more expensive so the bean counters won again .

I have worked on Motorhomes for 40 years and have NEVER seen that Monaco pump system. But, when the 12 volt pumps came out 25 years ago for RV's, they were in the $225 to $275 range. Now they can be found for about $125. I am calling the vanes that generate the vacumm a motor. Doug
oldave
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Aug 09, 2019
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Not sure what you mean by vacuum motor but there is no motor in the
black box . You are exactly correct , 12v operates an air valve ,
air is the passed thru the venturi to create vacuum as needed .
When done right the venturi is a terrific little devise but I suppose
the 12v pumps became so cheap and good where the black box probably
got more expensive so the bean counters won again .
dougrainer
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Aug 09, 2019
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oldave wrote:

Well lets update your Understanding.
1. RV Motorhome makes do NOT utilize Dash Air from the Auto Industry(including Monaco). They are supplied by companies that specialize in aftermarket Dash Air systems for the Motorhome market. Been this way for over 40 years. The only exception was the original 1979 thru about 1985 Silver sided Chevy Chassis Airstream motorhomes Class A
2. ALL DIESEL Dash AC systems use a 12 volt vacumm pump to supply the needed power to move the Air Damper doors when the Motorhome has a Vacumm activated system.
3. Most modern Diesels/Gas in the past 10 years or less use a Electric motor activated Damper door system Like a Denso system. I believe all Evans/tempcon use Vacumm systems. So, If you have Evans/tempcon you have a Vacumm system. Doug

Ok maybe not , guess I could have worded it better but some
components are plain old auto parts store stuff available most places
I can't say for sure but have been told my dash air control ( knobs etc ) are Ford .

As far as the vacuum pumps you are not correct when stating that they
are all elect . Monaco used an air through a venturi vacuum gen at
one time
Google will explain how it works . I located a picture of one on
a 2000 Windsor but couldn't post on here .

Maybe this link will work if anyone wants to see one .

http://www.irv2.com/forums/f115/vac-air-elec-box-above-generator-2000-windsor-403110.html

yes, I got the pic. From your original description I thought you were stating that by driving and the incoming fresh air operated some type of vacumm system. Now, I see the Chassis AIR system supplies the power to run the vacumm motor system. It still has 2- 12 volt wires, which I have no idea what they do unless they shut the vacumm motor on and off from a pressure switch like the 12 volt Electric ones do. THAT type system was only used on the Hi line Diesel pushers back then. Yes, some of the Dash components look like either Chevy/Ford or OLD Chrysler systems. But Evans/tempcon sells those parts if you cannot find them locally. Doug
oldave
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Aug 08, 2019
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Well lets update your Understanding.
1. RV Motorhome makes do NOT utilize Dash Air from the Auto Industry(including Monaco). They are supplied by companies that specialize in aftermarket Dash Air systems for the Motorhome market. Been this way for over 40 years. The only exception was the original 1979 thru about 1985 Silver sided Chevy Chassis Airstream motorhomes Class A
2. ALL DIESEL Dash AC systems use a 12 volt vacumm pump to supply the needed power to move the Air Damper doors when the Motorhome has a Vacumm activated system.
3. Most modern Diesels/Gas in the past 10 years or less use a Electric motor activated Damper door system Like a Denso system. I believe all Evans/tempcon use Vacumm systems. So, If you have Evans/tempcon you have a Vacumm system. Doug

Ok maybe not , guess I could have worded it better but some
components are plain old auto parts store stuff available most places
I can't say for sure but have been told my dash air control ( knobs etc ) are Ford .

As far as the vacuum pumps you are not correct when stating that they
are all elect . Monaco used an air through a venturi vacuum gen at
one time
Google will explain how it works . I located a picture of one on
a 2000 Windsor but couldn't post on here .

Maybe this link will work if anyone wants to see one .

http://www.irv2.com/forums/f115/vac-air-elec-box-above-generator-2000-windsor-403110.html
dougrainer
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Aug 08, 2019
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oldave wrote:
rasuth wrote:
I have a 2001 HR Ambassador. The Evans Tempcon P/N on the molded plastic evaporator housing is the same as referenced, and also has cracks. I was able to find a couple of PDFs of a service and trading manual (the web link doesn’t have much other than a knowledge base with little knowledge). The Newmar training pdf has a schematic of a typical pusher install wth a vacuum pump and reservoir (troubleshooting guide points to this), but my install has a box with the 12= supply, the vacuum line to the reservoir and a red polyethylene line going to the back. Is there an option to get vacuum from the diesel? I didn’t think that worked with a turbocharged diesel. Anybody know?

Here is the way I understand our air cond .
Monaco used dash air from the autos industry .
These air conditioners used vacuum to control system .
You are right that diesels don't generate vacuum like gasoline
engines so we have to generate our own vacuum
They did this by 2 different ways , one is a box looking device
that has a ventura inside where air is passed through to generate
vacuum . More recently they use a 12volt vacuum pump , borrowed from
auto industry , Ford I think .
Mine is mounted above the generator on the firewall .

Well lets update your Understanding.
1. RV Motorhome makes do NOT utilize Dash Air from the Auto Industry(including Monaco). They are supplied by companies that specialize in aftermarket Dash Air systems for the Motorhome market. Been this way for over 40 years. The only exception was the original 1979 thru about 1985 Silver sided Chevy Chassis Airstream motorhomes Class A
2. ALL DIESEL Dash AC systems use a 12 volt vacumm pump to supply the needed power to move the Air Damper doors when the Motorhome has a Vacumm activated system.
3. Most modern Diesels/Gas in the past 10 years or less use a Electric motor activated Damper door system Like a Denso system. I believe all Evans/tempcon use Vacumm systems. So, If you have Evans/tempcon you have a Vacumm system. Doug
wa8yxm
Explorer III
Aug 08, 2019
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If this is a plastic cover and you have a friend with a large enough 3-D printer....

NOTE there are companies that have large enough 3-D printers can print you up a "Xerox copy" as it were... Alas I do not know who they are.
oldave
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Aug 08, 2019
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rasuth wrote:
I have a 2001 HR Ambassador. The Evans Tempcon P/N on the molded plastic evaporator housing is the same as referenced, and also has cracks. I was able to find a couple of PDFs of a service and trading manual (the web link doesn’t have much other than a knowledge base with little knowledge). The Newmar training pdf has a schematic of a typical pusher install wth a vacuum pump and reservoir (troubleshooting guide points to this), but my install has a box with the 12= supply, the vacuum line to the reservoir and a red polyethylene line going to the back. Is there an option to get vacuum from the diesel? I didn’t think that worked with a turbocharged diesel. Anybody know?

Here is the way I understand our air cond .
Monaco used dash air from the autos industry .
These air conditioners used vacuum to control system .
You are right that diesels don't generate vacuum like gasoline
engines so we have to generate our own vacuum
They did this by 2 different ways , one is a box looking device
that has a ventura inside where air is passed through to generate
vacuum . More recently they use a 12volt vacuum pump , borrowed from
auto industry , Ford I think .
Mine is mounted above the generator on the firewall .
wq93
Explorer
Aug 08, 2019
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Many diesel engines were equipped with a small vacuum pump driven off the belt to provide vacuum for accessories. I suspect that some manufacturers may have also used electrically operated vacuum pumps and if you are trying to retrofit a vacuum pump to a system that didn't come with one that is probably the simplest approach.

Diesel engines won't provide a reliable vacuum source whether turbocharged or naturally aspirated because they don't have a throttle plate so there is very little air restriction on the intake side and thus no significant manifold vacuum. This is the same reason that diesel engines not equipped with some sort of exhaust brake provide very little engine braking compared to a gas engine which develops its engine braking by forcing the engine to pull air through a nearly closed throttle plate. With large diesels, a "Jake brake" discharges the compressed air at the top of the compression stroke to provide excellent braking while lighter duty/small diesels use some sort of exhaust restrictor to provide engine braking often in the form of variable exhaust vanes in newer turbo diesel engines.

Some of the newer DPF equipped diesels have a throttle plate to help heat the system during regen but this isn't intended to provide a reliable source of vacuum or engine braking.
rasuth
Explorer
Aug 08, 2019
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I have a 2001 HR Ambassador. The Evans Tempcon P/N on the molded plastic evaporator housing is the same as referenced, and also has cracks. I was able to find a couple of PDFs of a service and trading manual (the web link doesn’t have much other than a knowledge base with little knowledge). The Newmar training pdf has a schematic of a typical pusher install wth a vacuum pump and reservoir (troubleshooting guide points to this), but my install has a box with the 12= supply, the vacuum line to the reservoir and a red polyethylene line going to the back. Is there an option to get vacuum from the diesel? I didn’t think that worked with a turbocharged diesel. Anybody know?

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Evans Dash Air Nightmare

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