Author Topic: Did dash air repair alter engine cooling design  (Read 3723 times)

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Offline timjet

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Did dash air repair alter engine cooling design
« on: April 21, 2017, 03:33:45 AM »
I would like some opinions from those in the know about a dash air conditioning repair that has altered (in my opinion) the cooling design of my Cummins ISL, Spartan Chassis, '07 American Tradition with side radiator.

The cooling system as designed by Spartan consists of a radiator stack with the intercooler radiator on top followed by the engine cooling radiator, followed by the hydraulic cooling radiator (steering & fan motor) and on the bottom of the stack the air conditioning condenser.

The dash air conditioner repair shop determined the existing air conditioning condenser was faulty and in an attempt to save me some money and time decided to add an off the shelf air conditioner condenser to the back side of the cooling radiator stack which covers about 50% of the intercooler radiator and about 50% of the engine cooling radiator. They installed it with about an inch or so space between the stack and the new condenser. So airflow across the radiator stack flows from the fan through the radiator stack and then with about an inch space through the air conditioner condenser.

My concern is the airflow through the intercooler and engine cooling radiator will not be sufficient when the engine is under a heavy load, like climbing a 8% grade at 8000 ft. I called Spartan and explained the new installation to them and they could offer me no opinion as to this new installation saying only that if the cooling system is altered they could not say it will work properly. I was not talking to a cooling expert just a general tech. The dash air shop is telling me they have experience in this and the new install is OK.

I'm going to try attaching some pictures of the new install. The original condenser was left in place and the Freon lines rerouted to the new condenser. The original condenser is hard to see in the pictures but is the bottom most radiator. Each of the 4 radiators in the stack has the attachment bolts clearly seen in the pictures.

I would really appreciate some opinions on this new installation as it could save me a ton of money and is more efficient for the air conditioner but I do not want to affect the cooling to the engine or intercooler.

Offline Brett Wolfe

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Re: Did dash air repair alter engine cooling design
« Reply #1 on: April 21, 2017, 05:08:40 AM »
timjet,

Welcome to the Diesel RV Club Technical Website.

Placement of the dash A/C condenser as the first thing in the cooling package is a very common arrangement on side radiator coaches.

Two negatives, common to all of them:
1. Yes, they do add to the heat load by "pre-heating" the air going to the CAC, radiator, etc.

2. Most side radiator fans are controlled by a thermostat tuned to engine coolant temperature.  So unless the coolant temperature calls for the fan to run on a higher speed, air flow through the A/C condenser is often insufficient.  Said another way, the dash A/C will not work as effectively unless the fan speed is sufficient to provide adequate air flow.

Problem 1. is reasonably overcome by just turning off the dash A/C the few times you are on that 8% at 8,000' (or anytime engine coolant temperature rises excessively).

Problem 2.  Is one of those trade-offs (and a very good one IMO).  You are not paying diesel and HP to turn a fan on high all the time.  Reality in a DP is that the dash A/C does not have enough BTU's to keep up with anything but marginally hot temperatures-- just too many cubic feet to cool.  And, your diesel generator only burns a half gallon an hour running a roof A/C with quite a lot more BTU's of cooling. So, that is a reasonably option.

Offline timjet

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Re: Did dash air repair alter engine cooling design
« Reply #2 on: April 22, 2017, 03:30:12 AM »
Thanks Brett.

I've been warming up to the idea of keeping the off the shelf condenser in place. There is about 1 inch space between the original radiator stack and the new off the shelf condenser. Before the installation of the off the shelf condenser there was nothing in front of the existing stack, so I'm considering asking the dash air shop to increase the spacing between the radiator stack and the new condenser. I think I could get about 3 inch space between the two. That should increase air flow to both radiators and the heat generated by the new condenser should not affect the existing stack as much.

As mentioned in another forum adding a switch to manually turn on the fan is a consideration. I'm not sure what's involve in doing that or if there is any downside.

Offline Brett Wolfe

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Re: Did dash air repair alter engine cooling design
« Reply #3 on: April 22, 2017, 05:33:04 AM »
Check with Spartan to determine how your fan is controlled.  Some are electric, so a switch would work.  Others are thermo-wax controlled and that would not work.

Again, there are a LOT of side radiator coaches with exactly what you have after the modification.

I would not put additional spacer between the radiator and the condenser.  Would be afraid of the additional torque/leverage you would be adding to the condenser support as you hit bumps.

Offline ziggyh

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Re: Did dash air repair alter engine cooling design
« Reply #4 on: April 23, 2017, 07:39:24 PM »
Out of couriouisty, could the OEM condenser be separated and one fitted into the original location.
Haven't looked at mine and will when I get back to my motorhome for interist sake.
ZiggyH

2007 Revolution LE
C9