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OTR AC, the final solution!!

Yahoo Message Number: 94724
I have had an interesting couple of weeks with the OTR AC on my 2008 Allure. She went in for an annual service and MOT (UK government vehicle examination) and having been somewhat perplexed for the last 3 years with the quality of OTR AC I asked them to get a HVAC guy in to recharge the gas.
Well that was just the beginning!

They go to recharge the gas at the engine bay points and are not happy as they see a leak in the pipe at the swage joint. So the system is evacuated and vacuumed and a new pipe made up to replace. Now onwards with the recharge.
That gets done but the tech is not happy with the operation, with pressure and temp climbing and the cooling fan has not going into fast revs. He is led to the trinary pressure switch and by a process of jumping leads determines that the switch must be faulty as he can get the fan operating.
Without consulting me they go off and try to source a replacement, eventually routing to Evans Tempcon in the US who state that the trinary switch is no longer available from them, only a binary which they order. When I find out I make some postings on here and iRV2 and get feedback that these trinary switches are out there, contact CC which I did, and $118 plus delivery later it's on its way.
Switch gets here to the UK and Tech comes to my barn to fit it. No change. After a lot more trouble shooting he decides that the thermostat is wired incorrectly and changes that to bypass the pressure switch and now we have the system working as it should. Pressure and temp rising and then falling as fan cuts in. But I am puzzled why would CC have designed a system that fundamentally did not work. I ask the tech if any of the wires to the switch could just be incorrectly wired. Without a schematic he was stumped for an answer.
So I emailed Gregg again at CC and he sent over a schematic which is not in my Chassis pack. It shows the switch wire colours to the tag numbers of the CC loom, and I go to the coach to check and sure enough 2 wires are transposed.
So this coach came out of the factory wired wrong, the OTR AC can never have worked properly or efficiently and the original owner obviously did not pick this up."? Pete if your reading this let me have your opinion on that part"? So to any of you who are unhappy with your OTR AC, and I know there are some as its those sort of comments that led me to believe that my AC was just how things were...not like my Audi A7 that's for sure, so get the wiring diagram from CC and check your pressure switch, it's easy. Out the gen slide and it's up under passenger side.
You may find you own better OTR AC than you thought!!

Michael

2008 Allure 31683

Re: OTR AC, the final solution!!

Reply #1 –
Yahoo Message Number: 94744
Hi Michael,

Glad to hear you found your problem. I have found a number of wiring errors on our CC. Some mis-wired, one with no wire where there should have been.

Regarding the OTR AC, many have complained it doesn't work very well, me included. After doing some investigating I discovered that even though the heater was turned of there was still hot coolant from the engine flowing through the heater core. This effected the AC quite a bit and also the vent air. I installed a 3/4" ball valve in one of the heater hoses up above the generator. Easy to get to when the generator slide is open. This made a HUGE difference in the effectiveness of the AC. Before installing the valve in 70 degree weather the air coming out of the vent, with the AC off, was warm. Much warmer than the outside air temp. After installing the valve the OTR AC will keep us comfortable in 100 degree temps. True I need to have the fan on high and the air set to recirculate but it's a very big difference. Before the valve the AC would not keep us comfortable in 80 degree temps. I would send a picture but I can't get the generator slide open at the moment.

Barney

07 Inspire 52059

Re: OTR AC, the final solution!!

Reply #2 –
Yahoo Message Number: 94749
Michael,

What thermostat are you referring to? A stat in the A/C? What pressure switch? Would be great if you posted some pix of these items in situ. Of course we cannot assume that all years and models of CC had the same OTR AC setup, I assume? I am interested since my engine cooling fan does not seem to always respond to the OTR A/C until the engine has reached operating temp. The compressor cuts in and out until the engine warms up. Then it cools well.

Rich 2002 Magna

Re: OTR AC, the final solution!!

Reply #3 –
Yahoo Message Number: 94753
Rich the stat is the evaporator coil stat again up under the dash, open the gen slide and look up under. The pressure trinary switch is in the line as I described. I will try and take some pictures when I go down today.

Barney, the valve sounds interesting, my plan will be to see how my AC works, we are off next week for 3 months in Spain and it will start to get very warm on the way back in July so I shall know how good or bad the system is with everything wired correctly, then from that base point will examine the valve option if I suffer with the same symptoms. So will report back then!

Michael

2008 Allure 31683

Re: OTR AC, the final solution!!

Reply #4 –
Yahoo Message Number: 94768
Michael,

You might try this once you get on the road. After the engine has had time to fully warm up and you are traveling at highway speeds set the OTR system to 'Vent'. Then set the temp to the coolest setting, on mine that's fully counter clockwise. Then turn the fan on high. Let it run like this for a couple of minutes then feel the air coming out for the dash vent. It should be very close to the outside temp. If it feels a little warmer then installing the valve will help the OTR AC cool much better. All of this should be done in cool weather to better feel any heated air from the vent air. This is how I discovered my problem.

Have a great trip,
Barney

07 Inspire 52059

Re: OTR AC, the final solution!!

Reply #5 –
Yahoo Message Number: 94774
Thanks Barney that's a simple way to analyse the issue. And with that in mind I think I may not have the problem, as when last summer it was hot I used the Vent option as an alternate to the AC when on the motorways where a good amount of air was being funnelled in and the venturi affect came into play. But nevertheless I will do this during the summer.

On another point I do find that at cruising speeds, circa 50-60 the heating seems to be held back, this is the only way I can describe it, but as you slow down to 20-30 the heat is full on again (at whatever setting you have it). Its almost like the speed of the coach sucks the heat out backwards. Poorly explained but I hope you and others get the gist?

Michael

2008 Allure 31683, in the UK