Ac Install In A B67- Troubles

[Dale Hamilton]

This is my 3rd AC installation in my B67. This is going to be right- or else! Cab is very tight, heavilly insulated with marine lead foam, all firewall openings sealed or grometted and dark tinted glass. SO, air conditioning should be a piece of cake. Let me relate my experience. During the initial build I installed one of those slick little combination heat/cool units from Old Air Products. These are designed for limited space, as in street rods, and I installed it behind dash, drivers side, replacing the original heater. It fit fine and it worked- sorta. It would blow 50 degree air, but it just didn't have the capacity to deal with a 95 degree day here in the south. These units are "compromise affairs" too small to really cool or really heat. So, I disconnected it, leaving it in place to function on heat only. Next I bought a big underdash unit, cool only. from Vintage Air Products. There is no space under the dash on a B67 of course, but there is space on the floor betwen the two air seat bases, and thats where I mounted it. This was a big improvement, and it could handle 90 degree days just fine. But, it gets hotter than than here, and it was running full blast to keep you marginally cool. Not good enough either. About now I discover that there is a difference in condensors- round tube type for R12 and flat squart tube types for R134. I had the round type. And moreover, mine could not be mounted forward of the radiator- I had to mount it between the frame rails, horizontally just ahead of the 5th wheel- two mushroom fans forcing air through it. This week I swapped it out and installed the flat square tube type. Also broke all the hose fittings apart, cleaned them and installed new O rings- the green ones by the way- not black ones that are only good for freon. Then I buy the biggest cool only under dash evaporator- this from Wheels of Time in Philadelphia. I saw this unit in a buddy's car and it will blow your hat off- really moves alot of air and it has alot of cooling coils. It will go on the floor between the seats. Hopefully I'll get it today and install it this weekend. Will report my further experience. Maybe you chaps can benefit by knowing what does not work.

[Barry]

Dale, thanks for posting...this could be very helpful to users in the future...can you also post some photos? I would love to see your A/C setup between the seats...

[Dale Hamilton]

This is my 3rd AC installation in my B67. This is going to be right- or else! Cab is very tight, heavilly insulated with marine lead foam, all firewall openings sealed or grometted and dark tinted glass. SO, air conditioning should be a piece of cake. Let me relate my experience. During the initial build I installed one of those slick little combination heat/cool units from Old Air Products. These are designed for limited space, as in street rods, and I installed it behind dash, drivers side, replacing the original heater. It fit fine and it worked- sorta. It would blow 50 degree air, but it just didn't have the capacity to deal with a 95 degree day here in the south. These units are "compromise affairs" too small to really cool or really heat. So, I disconnected it, leaving it in place to function on heat only. Next I bought a big underdash unit, cool only. from Vintage Air Products. There is no space under the dash on a B67 of course, but there is space on the floor betwen the two air seat bases, and thats where I mounted it. This was a big improvement, and it could handle 90 degree days just fine. But, it gets hotter than than here, and it was running full blast to keep you marginally cool. Not good enough either. About now I discover that there is a difference in condensors- round tube type for R12 and flat squart tube types for R134. I had the round type. And moreover, mine could not be mounted forward of the radiator- I had to mount it between the frame rails, horizontally just ahead of the 5th wheel- two mushroom fans forcing air through it. This week I swapped it out and installed the flat square tube type. Also broke all the hose fittings apart, cleaned them and installed new O rings- the green ones by the way- not black ones that are only good for freon. Then I buy the biggest cool only under dash evaporator- this from Wheels of Time in Philadelphia. I saw this unit in a buddy's car and it will blow your hat off- really moves alot of air and it has alot of cooling coils. It will go on the floor between the seats. Hopefully I'll get it today and install it this weekend. Will report my further experience. Maybe you chaps can benefit by knowing what does not work.

[Rob]

This is my 3rd AC installation in my B67. This is going to be right- or else! Cab is very tight, heavilly insulated with marine lead foam, all firewall openings sealed or grometted and dark tinted glass. SO, air conditioning should be a piece of cake. Let me relate my experience. During the initial build I installed one of those slick little combination heat/cool units from Old Air Products. These are designed for limited space, as in street rods, and I installed it behind dash, drivers side, replacing the original heater. It fit fine and it worked- sorta. It would blow 50 degree air, but it just didn't have the capacity to deal with a 95 degree day here in the south. These units are "compromise affairs" too small to really cool or really heat. So, I disconnected it, leaving it in place to function on heat only. Next I bought a big underdash unit, cool only. from Vintage Air Products. There is no space under the dash on a B67 of course, but there is space on the floor betwen the two air seat bases, and thats where I mounted it. This was a big improvement, and it could handle 90 degree days just fine. But, it gets hotter than than here, and it was running full blast to keep you marginally cool. Not good enough either. About now I discover that there is a difference in condensors- round tube type for R12 and flat squart tube types for R134. I had the round type. And moreover, mine could not be mounted forward of the radiator- I had to mount it between the frame rails, horizontally just ahead of the 5th wheel- two mushroom fans forcing air through it. This week I swapped it out and installed the flat square tube type. Also broke all the hose fittings apart, cleaned them and installed new O rings- the green ones by the way- not black ones that are only good for freon. Then I buy the biggest cool only under dash evaporator- this from Wheels of Time in Philadelphia. I saw this unit in a buddy's car and it will blow your hat off- really moves alot of air and it has alot of cooling coils. It will go on the floor between the seats. Hopefully I'll get it today and install it this weekend. Will report my further experience. Maybe you chaps can benefit by knowing what does not work.

What is the square inches (surface area times rows of tubes) of both your evaporator, and condensor? What are your suction, and discharge pressures? Average temperatures, and humidity levels encountered? R-134 readily accepts, or absorbs heat, but is slow for heat rejection. This is the reason for the design difference in the two condensors. A square tube has more surface area for heat rejection. Condensor design, placement and proper airflow are critical. You do not mention ducting for the "muffin" or axial fans forcing air through the coil either. Also, what type of expansion device is incorportated into the system. Do you have an accumulator or receiver/drier with a sight glass?

Because of static/dynamic and radiant heat loading in a motor vehicle application, you can just about double or even triple the needed cooling capacity for mobile applications as opposed to household needs. Just keep in mind that you also need to dehumidify the occupied space rather than just make it cold to be comfortable.

If you place a "too large" capacity air conditioner in a space, a person will not be comfortable, but will be cold. Also, if you are like me and ride with your female companion, your ears will be on fire.

Rob

[Dale Hamilton]

Rob- don't know evaporator, condensor is 16x24x1 sized to fit evaporator. Don't know pressures- I have to take the truck in to the shop to get it gassed up. I pur condensor the only place I could- between frame rails. No muffin fan ducting- they are zip tied to the condensor - two fans biggest I could find- bigger than the condensor in fact. Don't know expansion device- it comes with the evaporator. Yes have dryer- biggest one I could find. I want it cold. SWMBO can bundle up.

[Rob]

Rob- don't know evaporator, condensor is 16x24x1 sized to fit evaporator. Don't know pressures- I have to take the truck in to the shop to get it gassed up. I pur condensor the only place I could- between frame rails. No muffin fan ducting- they are zip tied to the condensor - two fans biggest I could find- bigger than the condensor in fact. Don't know expansion device- it comes with the evaporator. Yes have dryer- biggest one I could find. I want it cold. SWMBO can bundle up.

You mention the condensor is horizontal between the frame rails. Is it standing up, or laying down? How much higher is the compressor than the bottom of the condensor?

Rob

[Grease Monkey]

This is my 3rd AC installation in my B67. This is going to be right- or else! Cab is very tight, heavilly insulated with marine lead foam, all firewall openings sealed or grometted and dark tinted glass. SO, air conditioning should be a piece of cake. Let me relate my experience. During the initial build I installed one of those slick little combination heat/cool units from Old Air Products. These are designed for limited space, as in street rods, and I installed it behind dash, drivers side, replacing the original heater. It fit fine and it worked- sorta. It would blow 50 degree air, but it just didn't have the capacity to deal with a 95 degree day here in the south. These units are "compromise affairs" too small to really cool or really heat. So, I disconnected it, leaving it in place to function on heat only. Next I bought a big underdash unit, cool only. from Vintage Air Products. There is no space under the dash on a B67 of course, but there is space on the floor betwen the two air seat bases, and thats where I mounted it. This was a big improvement, and it could handle 90 degree days just fine. But, it gets hotter than than here, and it was running full blast to keep you marginally cool. Not good enough either. About now I discover that there is a difference in condensors- round tube type for R12 and flat squart tube types for R134. I had the round type. And moreover, mine could not be mounted forward of the radiator- I had to mount it between the frame rails, horizontally just ahead of the 5th wheel- two mushroom fans forcing air through it. This week I swapped it out and installed the flat square tube type. Also broke all the hose fittings apart, cleaned them and installed new O rings- the green ones by the way- not black ones that are only good for freon. Then I buy the biggest cool only under dash evaporator- this from Wheels of Time in Philadelphia. I saw this unit in a buddy's car and it will blow your hat off- really moves alot of air and it has alot of cooling coils. It will go on the floor between the seats. Hopefully I'll get it today and install it this weekend. Will report my further experience. Maybe you chaps can benefit by knowing what does not work.

[Grease Monkey]

Dale, assuming from your post, your dash A/C is not plumbed in at this time. If this is so, why not consider teeing the dash unit into the refrigerant system. Also, be sure the condenser is not lying flat. The outlet line on the condenser (line going to drier/expansion device/evaporator) must be lower than the discharge line coming coming from the compressor. This is so liquid refrigerant floods the evaporator core. I realize that your condenser will be rather small for the combination of evaporators, but it would certainly be worth a try. Generally speaking, I feel your compressor should not have a problem suppling enough refrigerant.

I live in south Texas and regularly drive my B model Mack in 95-105 deg. temperatures and bright sun. I rigged my system up as explained above. I purchased my components from Danhards near Dallas. We probably have similar units under the dash, however I have 36" sleeper on my truck. Under the bed I mounted a medium sized box unit (A/C-heater) and ducted into the sleeper compartment. My condenser is about the same size as yours, with two electric fans mounted to it. For lack of space, I mounted my condenser vertically between the left frame rail and driveshaft under the sleeper. Locating the condenser in this position is not a good practice because it gets little or no ram air at highway speeds, but it does work acceptably well. Some riders have commentented "you could hang meat back here!"

Grease Monkey

[Dale Hamilton]

Guys- The condensor does lie flat between the frame rails. And the compressor is probably 25" above the condensor mounting. I have seen condensors mounted this way, infact they sell whats known as a remote condensor- the only difference I ca see is the shrouding. Are you saying that a condensor can't be mounted flat>

Have not thought of t ing the second underdash evaporator with the new one. This sounds like problems however

[Rob]

Guys- The condensor does lie flat between the frame rails. And the compressor is probably 25" above the condensor mounting. I have seen condensors mounted this way, infact they sell whats known as a remote condensor- the only difference I ca see is the shrouding. Are you saying that a condensor can't be mounted flat>

Have not thought of t ing the second underdash evaporator with the new one. This sounds like problems however

I suspect your condensor coil is plugging from the accumulation of oil in the tubes. A condensor coil, (heat exchanger) can be laid flat or horizontal if it has a oil drain line that connects to the receiver/dryer. The refrigerant pulses from the discharge (high side) of the compressor; This pulse "punches" through the receiver/dryer media causing the output from this device to be a "fog" of both oil and refrigerant. I suspect you have pooling of refrigerant oil in your condensor coil and that is restricting the flow to the evaporator through the expansion device. From your description of the symptoms, you are starving the evaporator of refrigerant. The amount of refrigerant that does get through the expansion device to the evaporator coil is doing it's job and readily absorbing heat from the conditioned air space. There is just not enough to do the job satisfactorily which is the case with a low charged system. Realistically speaking, the bottom of the condensor coils should be almost the same elevation as the receiver/dryer to facilitate the "running off" of oil. This is not always feasible, but within 6 to 8 inches will suffice most times. It sounds as if you have an extreme difference in mounting heights and you are trying to push this "fog" I mention uphill. As the refrigerant cools a bit after leaving the compressor, and with the friction of the oil on the inside of the tubes, you are probably getting "drainback" to the condensor and the result is the restriction or "pooling" that I mention.

If you could stand your condensor upright about eight inches behind the cab and use one 16"-18" ducted fan to force air through the core, I feel your problems would be history. You will never get the "ram air" effect, but a proper ducted fan will work wonders and there is enough airflow available in this given space. It also would not be overly difficult to fabricate an aluminum, or fiberglass "chin scoop" to grab some of the air that passes under the truck during normal operation. This could be painted to match the cab and depending on your tastes, would have a nice appeal.

If you still run into difficulties, stop by my place on your trip to Peoria as I'm 20 miles west on Rt. 116 in the town of Farmington, IL.

Rob

[HeyCharger]

If Rob or Grease Monkey are still here, can they post photo's and details, please.

I'm a little tired of getting heat soaked and I've tried a lot of insulation.

So I may opt for air conditioning. I've noted that I do not need a heater.

Regards, Rod.