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Dodge Sprinter Heat/Air Conditioning Questions
I have the small wheel-base Sprinter Van. I would like to install a Roof-top Air Conditioner, however, I'm not having any luck finding information about MB factory or aftermarket units. I would really like the lowest profile unit available on the market. Any suggestions would be greatly appreciated. Thanks.
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The interior rear unit is the evaporator, and provides rear cabin air circulation, dehumidification, and cooling as the liquid refrigerant expands into gas across an orifice and/or capilary tube. The restriction of the orifice allows for a greater total pressure drop acoss the evaporator to concentrate the cooling effect in the coil where it is needed and provides a point in the system for the compressor to pump against in order to build up the required pressure that allows for the high pressure/high temperature gas to be forced across the gas/liquid phase boundary in the condensor with only ambient (normal outside temp) air being drawn across the condensor coil.
The Phase change is the key... phase changes require vastly greater temperature changes in order for them to occur and that is the key to BOTH condensing the gas (fluid) to liquid (fluid) and evaporating the liquid back to gas to get the chilling effect inside the cabin where it is needed.
Hope this is a clear explanation and that condensing (outside, heat dispersing unit) and evaporating (inside, cooling unit) is more clear to the group now.
That said, the majority of the aftermarket roof unit that we have seen for the Sprinter have been RV units and are meant to run on LAND power, or a generator system. I am not aware of any (RV units) that would be run on 12v or from the Sprinter with existing Daimler/Chrysler, as the draw on the alternator would be HUGE. but with a 200 Amp Alternator, it could probably be done with a smallish unit.
Thanks,
KenB
PS... If my explanation of Condensing/Evaporating is too much, please forgive me... I was trained as a technical person with all the required thermodynamics and to continue a thread with consensation/evaporation reversed was driving me just a bit nuts and I might get carried away.
1) it would possibly be feasible to install a factory rear unit on a van which wasn't built with one. But since the condensing apparatus is in the engine compartment and presumably powered by a belt driven compressor, then it seems much more difficult to retrofit a Sprinter with a factory a/c unit.
2) there would have been the possibility of running the rear a/c off the electric hook-up via a power converter.
For years there have been proposals to fit autos with electrically powered a/c compressors (with the compressor mounted to the body of the car (e.g. firewall in the engine compartment). This was enable the use of a hermetically sealed compressor, hard refrigerant lines, and so allow the use of more efficient refrigerants (freons)than the ones formerly required for cars due to the flexible hoses being susceptable to degradation by certain freons.
A couple of years ago I did see a new Sprinter for sale at a dealer in Dallas which had had an aftermarket rear a/c added. This unit was on the top back, but took up more space in the interior and extended less above the roof. I don't remember the additional price, but I do remember it was shockingly high. I'd forget about trying to retrofit rear a/c to a Sprinter.
1) compressor in engine compartment (second pump)
2) Condensor in gray box on rear roof (extra electrically driven fan to consense refrigerant)
3) Evaporator inside in rear to cool/dehumidify/circulate the air.
Sounds like a system to steal off of a wrecked Sprinter (sweat equity is wonderful if you can swing it)...
Thanks,
KenB :shades:
This would seem to mean that retrofitting with a factory unit might not totally our of the question, but would still cost a bundle.
What is the standard arrangement for a large minivan with rear a/c?
The interesting thing is that the A/C unit on the Safari works Much Better in the front when the rear is turned on low and allowed to circulate its share of the freon, even though the rear air, on low, gives only a little cool air.
What I am saying is that the Front air (coming out of the vent) is MUCH cooler when the rear is allowed to circulate its Freon (even on the hottest day, right when you fire it up and try to cool down) before the rear actually contributes to the coolness of the cabin air.
My guess is that the freon stacks up in the plumbing going to the rear and does not let any of that part of the charge circulate back to the compressor and starves the front for freon flow... but then the LONG return line from the back should always have the low-pressure (evaporated fluid/gas) in it while the compressor is running and that should be available for the pump to draw from anytime it is low?
thanks,
KenB :confuse:
The entire set-up may be overcharged with freon unless the rear unit is also on, which is another way to say what you said. The fren charge could be within specs and just works that way or it could be outside specs.
Getting back to the Sprinter rear a/c unit, the temperature of the compressed gaseous freon is 125 deg F or so, maybe higher, before it gets to the condensor coil where it is cooled to outside ambient temperature and condensed to a liquid. I know on my car (91 dodge Spirit with R-12 freon) the line going into the condensor is too hot to grasp. The Sprinter must have that line insulated or it would be an unwanted heat source.
The return line is (as Always) larger in order to pass the expanded gas back to the front and in most applications is more likely to be insulated so that it does not sweat and does not continue to gain heat from the ambient temp. (that helps the compressor run cooler and have to compress the gas less to get it back to full pressure on the hot/consensor side.
The receiver/dryer chamber allows any liquid/two-phase fluid to return to gas before being sucked into the compressor... liquid in a gas compressor is bad...
KenB :shades:
I have found some information that might be helpful to you.
First you can go to the dealer parts department and get a copy of all the parts for their rear ac unit with part numbers. Also here are some links for real information on how the system performs. Their is alot of good information at this link about what you can expect from owners.
http://www.sportsmobile.com/2_sr_heatingcooling.html
The next link uses another way
http://www.espar.com/htm/aircondition.htm
Their is another link I called and talked to them about ac systems for comfort(they do refrigeration for sprinter only.) but are going to make a rear ac unit (like vans have now) for the 07 sprinter first, then others will follow. but I will have to find it and send it to you.
Hope this helps
Bill Melville
My email is wmelvillejr@yahoo.com
http://www.sprinter-wiki.com/wiki/index.php?title=SCS_Frigette_Installation
The condensor unit is installed underneath the vehicle.
Under high humidity, I have actually had moisture spit out of the top of dash vents (above/either side of, the radio), and those vents were also wet with drops of condensed moisture.
The van was full of noisy teenagers (as it usually is) and I did not hear any misty-moisty noises... but I could imagine there could be some since I got Spritzed at least once, leading me to touch the wet vent in the dark. After touching the problem spot, I could see the leetle round droplettes in the moonlight or streetlight.
KenB :shades:
When it is cool outside I open the vents for cool fresh air and without warning and not touching the temperature control knob the air becomes hot. It may stay warm or go back to cool. This happens with no time frame being the same. Help, I am trying to get this fixed without going to the dealer.
This also plays havoc when the a/c is running.
is your temp control all the way on the cold stop?
If not, the warm temp will come on regardless of air temp (air flow that is) if the engine is warmed up. A sensor, not sure where, will try to get the temp to a sliding-scale temp.
Cold stop is only cooling, just off the stop appears to still give very little heat except at COLD temps (but with the engine temp up). Just beyond the cold stop, some heat is added until the sensor (wherever it is) gets up to about 62F.
As you run the temp know up the scale, the air flow will be more and more warm, for a longer and longer time until that elusive sensor is up to the temp for that spot on the dial... It is not the (flowing) air temp that is affectively controlled by the knob as you are used to in most American cars, but rather the temp of the sensor. Until warmth gets to the sensor, the heat will remain flowing unless you have the knob on the Cold stop.
If you are on the COLD stop and you get heat, then the control may be bad... I see them for sale on EBAY once in a while, usually the entire air control cluster.
Write back if you have more diagnostic info after reading the listing above.
KenB :shades:
thanks dave
thank you for all the insight on this system. I have an alldata account, but I still can't find the high and low side test port for the rear compressor. would you please let me know where to look for them? I would like to test prior to sending it in for service.
thank you in advance,
cg
thx,
cg