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Custom System/Conversion Not Cooling

Kawgomoo on Mon May 23, 2011 2:42 AM User is offlineView users profile

Year: 1989
Make: Dodge
Model: Ramcharger
Engine Size: Cummins
Refrigerant Type: r134a
Ambient Temp: 90
Pressure Low: 30
Pressure High: 250
Country of Origin: United States

I have an 89 ramcharger that i swapped a 97 cummins diesel into.

the ramcharger had an r12 system, though the ac compressor on the engine was always designed to be r134

i have placed a 12x26 parallel flow condenser in front of the truck. in front of the radiator and intercooler.

The radiator is cooled by 2x12 electric fan unit.

Used a new drier and custom hoses to plumb it all together.

Replaced the txv

Flushed entire system with 1.25 gallons mineral spirits. Components were isolated and flushed one at a time. Didnt flush the drier or compressor

blew everything out with shop air and inline desiccant driers.

pulled vacuum for about 2 hours or so.

hooked up can, purged yellow line at manifold. let vacuum suck in can through low side engine off.

put in 2 more cans slowly.

i have charged it twice now with varying levels of liquid and still piss poor results.

vent temps never lower than 58 which is at idle. 60-70 while driving.

is it possible i just dont have enough condenser?

spraying water on condenser lowers high side pressure but doesnt seem to help cooling.

please help, its really hot out here!!!



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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

mk378 on Mon May 23, 2011 9:22 AM User is offline

Pressures look generally OK. Is the low side line getting cold? If so the evaporator would be cold and you should consider reheating from the heater core or other airflow issues in the cab.

Three cans is probably not enough for a truck system like that. The engine fan is vital for proper cooling. With conversion to diesel engine make sure the pulleys are set up for proper compressor rpm. Check that receiver drier is mounted vertical and plumbed properly so it will draw liquid out of the bottom (it has a dip tube on the OUT line) and feed solid flow of liquid to TXV. Check that TXV sensor bulb is secure on the side of the evaporator OUTLET line and well insulated from external heat.

Kawgomoo on Mon May 23, 2011 12:34 PM User is offlineView users profile

32 oz is the recomended charge for this truck, i believe it holds 44 oz of r12.

The ac compressor along with everything on the diesel engine is exactly as it was equipped from the factory for a 97 dodge ram. i just put it in another vehicle. So compressor speed and pulley ratios are still of factory spec.

Temp sensing bulb for the TXV? You got me on this one. there is no remote bulb or anything like that the txv is all one unit with nothing hanging off it or anything like that. i can take a picture if youd like....it looks exactly like the one it replaced.

the txv block is not insulated at all. neither is the suction line.

the suction line is cold and sweating. i coulda have sworn i saw ice form on it the other day.

the liquid line is warm, but not hot. Will have to check the receiver i know it was kind of laying over a little bit. maybe 15 degrees i will make sure it points straight up.

i also popped the recirc vent open on the heater box so i could get my hand in there and clean out all the debris. lots of pine needles, but made no difference on the cooling of the system.

is it possible the evap is somehow clogged?

when i drive, i hear this occasional hissing from beneath the dash....like water droplets hitting a hot frying pan. usually when i hit the brakes i hear it. not sure what it is. possible obstruction in the evap perhaps?

is it possible this condenser is just not big enough? the oem condenser is like 18x28 this one is 12x26 but is a parallel flow unit.

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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

Kawgomoo on Mon May 23, 2011 12:38 PM User is offlineView users profile

but i will try and add more freon! my gut feels like it may be a little low, but i dont want to overcharge this sucker either.


oh yeah, forgot to mention. my low side cutout switch is not adjustable. so its still set for r12 {about 28 i think} could this be part of the problem?

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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

Edited: Mon May 23, 2011 at 12:50 PM by Kawgomoo

bohica2xo on Mon May 23, 2011 2:56 PM User is offline

A cold or frosted suction line says something is getting cold - just not the vent air.

A blend door issue, or hot water shutoff issue most likely.

The LPCO is easy enough to swap for an adjustable unit, but for now it is not the root of your bigger problem.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ice-n-tropics on Mon May 23, 2011 2:59 PM User is offline

I'd install a hand operated valve in the heater hose and be sure the fresh air door was fully in the recirculation mode.
hotrodac

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Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

Edited: Mon May 23, 2011 at 3:01 PM by ice-n-tropics

Kawgomoo on Tue May 24, 2011 3:16 PM User is offlineView users profile

i pulled a cover off the front of the heater box.

It seems to be a diverter duct that directs the hot or cold air up into the dash plenum.

If i put a thermometer inside this box its 40 degrees in there.

i can also reach in and see part of the heater core. with the air off and the water shut off the heater core is hot to the touch.

I think shutting off the hot water will help alot here..... it seems like its forcing the cold air backwards through the heater core when this diverter duct is in place.

duct pressure still seems low, is there a good way to seal up the ductwork inside the dash?

i also pulled the blower motor and hosed out the evap, then reinstalled blower with dum dum around the flange as the stock gasket was shot..blowing cold air under the hood and sucking heat off the turbo.


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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

Kawgomoo on Tue May 24, 2011 4:10 PM User is offlineView users profile

Alright back to square one. Apparently i only got the icey temps yesterday cause the evap was still soaking wet.

Today its about 100 outside {phoenix}

trucking idling, temps inside the box 56-60

pressures were 25/325-350

sprayed water on the condenser pressures stayed at about 24/175

the low side would run anywhere from about 19-25psi

high side was pretty solid at 175 as long as condenser was wet.

during this time i reached my hand inside the heater box. the bottom half of the evap was warm to the touch and the top half was cold.

So under charged with a condenser that cant keep up? due to airflow or whatever reason? am i getting close?

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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

bohica2xo on Tue May 24, 2011 9:22 PM User is offline

Well, there is the rest of the problem - electric fans.

Without enough condensor airflow, you will see those high pressures and poor cooling.

Put the mechanical fan back on, and make sure the shroud fits well. Make sure no air bypasses anything in the heat exchanger stack.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Kawgomoo on Wed May 25, 2011 12:33 AM User is offlineView users profile

there is no hope of engine driven fan and or the shroud ever making there way back onto the vehicle.

this is a diesel conversion in a truck it was never meant for... there simply isnt enough room. thats why the condenser is where it is instead of where it should be.

i am going to toss a few more pusher fans on front of the condenser and hope its enough to keep the temps down...its my only hope.

my rear rocker cover is up against the firewall already..so no way to move the gigantic engine any further back either

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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

Kawgomoo on Fri June 03, 2011 7:47 PM User is offlineView users profile

Alright guys, here is the update....

i added two 9" pusher fans in front of the condenser. it doesnt really seemed to have helped a whole lot.

Here is the setup again.

89 dodge ramcharger
97 cummins diesel swap w/ r134 compressor
12x26 parallel flow condenser
2x12 FAL puller fans w/shroud on radiator
2x9 pusher fans on the condenser
All new lines w/barrier hose
New H Block

When charging the system i vac it for about 2 hours. then start with one can and work my way up to three cans of r134.

Somewhere around 1.5 cans the system will start to cool at about 60 degrees vent temp.

At this point pressures are about 20 lowside 150 high side.

Slowly adding refrigerant makes the high side pressures increase proportionality with the amount added. But the cooling never improves.

Once the system is pretty much maxed out at around 2.5 cans pressures are running at about 20 low 400 high.

The low side pressure never really seems to increase, and the high side pressures are stable at any given charge level of r134.

What could possibly be going on here?

is a 12x26 condenser just way too small for whatever size evap is in the dash?

Could my condenser be too close to the intercooler restricting air flow? {they are as close together as i could get them..maybe 1/8" apart}

any help is greatly appreciated, it is HOT out here in az and this just isnt cutting it. My kid is frying back there.

I plan to add rear air if i can ever get this front sorted out and blowing cold....

If i need a bigger condenser then let me know! at this point i am ready to cut the front of the truck apart and fit whatever size condenser i need in there so long as that will make this bitch blow cold!!!!!

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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

tomw on Sat June 04, 2011 12:12 PM User is offlineView users profile

I'd do some quick math on square feet of condenser, comparing the old to the new. You made a significant change in the amount of 'finnage' that is exposed to ambient, to transfer the heat. You took away almost 38% of the fins, and area exposed for heat transfer.
From memory, it seemed that R134a systems always needed more condenser than R12 systems. You went the other way. Your old condenser had 504 square inches, and the new has 312, both approximations. The serpentine vs parallel won't add enough efficiency, in my opinion, to make up for the reduction.
Find out the size condenser put into the current or equivalent vintage Ram's using R134a. The engine being gas or diesel shouldn't make a bit of difference.
Just my 2 copper-clads...
tom

add: Did you check the diameter of the pulleys on a diesel vs a gas engine? In most cases, the diesel never turns the rpms that a gas engine does, so you may want a smaller crankshaft pulley. Again, I'd check the diameter spec'd by ChryCo. They have engineers that do this stuff for a living, and have satisfy customers or they'll get bought by the Italians... Oh, wait.... Never mind.
t

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simplificate and add lightness

Edited: Sat June 04, 2011 at 12:15 PM by tomw

Kawgomoo on Thu June 09, 2011 8:42 PM User is offlineView users profile

I totally agree with not enough condenser! Can you run some quick math and tell me what size i should go with?

I would have used the condenser that came off the late model ram that i pulled the motor from, but it had a hole in it.

I had originally intended to use the condenser, radiator, clutch fan and intercooler from the late model ram but it was all damaged.

if i move the condenser to between the radiator and intercooler i can fit something in the range of 22x31.

think that will be enough for me?

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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

Kawgomoo on Thu June 09, 2011 9:08 PM User is offlineView users profile

the ram oe unit is 17 x 24 give or take.

http://www.autopartswarehouse.com/sku/Dodge/Ram_3500/Spectra/A-fs-C_Condenser/1997/Base/6_Cyl_5-dot-9L/SPI74579.html

if i am going to redo this i want the largest condenser possible!!!

oh yeah with a 8 inlet and 6 outlet on the condenser, which line should be on top? {if it matters which way the condenser is flipped}

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89 Ramcharger, 97 Cummins Conversion, 12x26 Parallel Condenser, Electric Fans

tomw on Mon June 13, 2011 2:17 PM User is offlineView users profile

I'm re-doing... missed the point.

So the factory part is 17X24, does that mount before the intercooler? Hope so. You may be doing yourself a dis-favor putting the A/C behind any other 'heat exchanger'. The engine will just have a little less HP if the intercooler has +10 hotter air going by, but the A/C has a much more limited temperature range where the refrigerant will function. Adding decreased heat rejection will of course lead to warmer vent temps.

I thought that the 'hot' should be at the top, and the cool would naturally sink to the bottom, to be sent off to the TXV, but don't bet your paycheck. I am assuming that the larger is the gas coming in and the smaller is the 'liquid' coming out.
tom

Last edit: I agree. I would put the largest condenser I could fit in there. Lower head pressure, and more 'working range' before deterioration of performance.
tom

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simplificate and add lightness

Edited: Mon June 13, 2011 at 2:33 PM by tomw

chris142 on Mon June 13, 2011 7:54 PM User is offline

As far as the dash ducts not working. The original Gasoline engine use engine vacuum to control the doors in the dash. Diesel engines don't have vacuum.

Your Cummins Diesel may or may not have a vacuum pump on the back of the injection pump to operate the power brakes and dash controls.

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