New truck, no ac, dealer says its normal?

[Wrongway]

Ok, here is the deal. We recently got a new 2015 pinnacle. It has the 505 horse MP8, the M-Drive auto tranny. I drive this truck everyday and I love it. But, now that its getting hotter outside, I noticed that the ac doesnt work as well as it should. If Im driving the truck down the road, I will get vent temps of right around 40 degrees. Which is great! But, when Im sitting, getting loaded, or waiting on something, the vent temps get up to about 60 degrees. I was kinda debating on taking it back to the dealer. I mean it IS working, it could be much worse, don't want to be a cry baby kinda thing. But, then I got to thinking. We paid $120,000 for the truck, and the ac wont work??? So yeah, it went back.

The first time it went in, they said it was 40 at the vents sitting or driving. All the pressures were fine, nothing wrong with it. Then I reminded them that the day they tested it, it was only 60 degrees that day. Its not real hard to cool to 40 if you start at 60! They said bring it back on a hotter day.

So, the other day it was about 95, and I take it back to them. Park outside, walk in, explain the whole story to them, and they tell me that there is noting wrong with it. That's common, some trucks are just like that. I tell them that I think its an airflow problem. If I rev the truck up a couple hundred rpms and hold it there for a while, it starts to get cooler. Like maybe the fan isn't kicking on or something? They tell me that the head pressure controls the fan. Once the head pressure gets to about 300-350, the fan comes on and brings the pressure back down. About the only advise he could really give me was "if your going to be sitting for a while, just kick the rpms up and set the cruise control"!

Im looking for ideas. I had an idea of adding a electric fan that would kick on when the compressor was on. But there isn't really any room in front or behind the radiator. PLUS, that would probably kick out any warranty.

Though about unhooking the electric to the fan that's there now. That should make it stay on all the time. Try that for a day or so, just to see if it helps or not. But worried that it will trip the check engine light.

Thought about going back to the dealer and throwing a fit, but not sure that will help either.

Anybody have any more ideas???

[Dirtymilkman]

Wtf?! That's definitely not right! My 2015 is ice cold idling or driving. And if your service guy has any brains he should know that these engines are not supposed to be idled up. 550 to 700 rpm's but never above that. These dealers sure can give trucks a bad rap. I would have it back to a good dealer immediately. There should be no excuses like you were told

[Macktech689]

I've worked at Mack dealerships for almost 20 years and I agree your dealer is full of BS, you should be able to hang meat in the cab at idle. Unfortunately I can't fix it from here, I have had to replace a couple of control panels on 2015s to repair A/C system drop out, cant be sure this is your problem.

[Wrongway]

Now see, that's what I was thinking too! Guess I will make a call to my local dealer and try to go over the service guys head. I hate to have to do it that way. But, like I said, its a $120,000 truck with ac problems. And I would understand if it was some sort of a brand new system, that nobody knows anything about. But, it ac, its been around a long time, and it isn't that complicated!

On a side note, I was talking to a friend of mine that has a new 2015 Granite. His truck was doing the same thing mine is now. He took it to the same dealer as mine. They found a bad fan and expansion valve. Replaced both, now his blows 36 degrees at the vent sitting or driving.

[mrsmackpaul]

mate sounds like it has a shortage of gas not a lot because it still works fine when the compressor is spinning fast shifting heaps of gas real quick just enough so that although system is working fine there isnt enough gas going to the evaporator (the bit in the dash) for it to work properly and get ice cold when the truck idles if that makes any sense the dealer is full of crap it should be chilly all the time

At least thats my thoughts maybe the gas works different up side down

Paul

[220cummins]

From my documents

[Wrongway]

I don't have one. No electrical on the dryer, only hoses. But, thanks though!

[220cummins]

It would be inline on the drivers side towards near the rad.

[Wrongway]

Ok, I think I found it. There is two switches right next to each other on the black line. Not sure if it's the high or low pressure line. There is a silver (aluminum) line and a black line. Any ideas on which switch it could be? And also, I remember unplugging the switch on the dryer and jumping it out, on other older trucks. Could I do something like that for a day or so, just to try it out? Just trying to make sure of what the problem is before I go back to the dealer and explain them their job!

[Murf915]

Except for the AC breaking in my CHU the second week i had the truck, the AC blows real cold in my mack all the time now. Like you said its brand new truck, it should have no issues

[ws721]

Wtf?! That's definitely not right! My 2015 is ice cold idling or driving. And if your service guy has any brains he should know that these engines are not supposed to be idled up. 550 to 700 rpm's but never above that. These dealers sure can give trucks a bad rap. I would have it back to a good dealer immediately. There should be no excuses like you were told

Why wouldn't you bump the idle when sitting still? I thought all engines are better off when at a high idle if left running for an extended period of time? Just wondering

[Dirtymilkman]

Something with the emissions bs. I know when mine idles it actually will build boost pressure at 650rpm. The visor sticker says truck can be idled indefinitely at 500 to 700 rpms but never elevate the idle.

[bts-4120]

I believe you plug the dpf in a hurry if you idle it up for extended time

[Mackpro]

Probably a fan clutch issue. Is your fan clutch huge with aluminum heat sink fins on it? If so, its a Borg Warner Cool Logic and they are junk. We have a 2015 here that has had 2 replaced and we finally changed over to the Behr type fan clutch. Look for signs of oil specks splattered on the front of the engine. If you have the Horton air fan or the Behr type your OK.

[rick harper]

possible that the hot water valves are still open. close them if they are open.

[rsb502]

These guys are maroon's.......its obviously an issue with your muffler bearings, have you tried lubricating them with 30wt light bulb oil?

[Wrongway]

The water valves are closed. There is actually 2 of them, wasn't expecting that! But, they are both closed. And, I'm not sure which fan it has. I'll look in the morning and let you know. Thanks for the replies and ideas.

[Lmackattack]

Something with the emissions bs. I know when mine idles it actually will build boost pressure at 650rpm. The visor sticker says truck can be idled indefinitely at 500 to 700 rpms but never elevate the idle.

Intresting. I always bumped up my idle when I was sleeping at night and needed A/C or heat. I would set it to about 700 or so....I also kept the fan on so it was always moving fresh air across the engine.

It was more to keep oil press up a little higher...I keep the fan on also to keep it from cycling on/off every few minutes be it the water temp or A/C unit telling it to do so.

This is a 3406E Cat

[Wrongway]

Looks like I have the Borg Warner fan. Big round aluminum piece between the fan and the pulley. But, the front of the fan is dry. Dosent look like it's leaking oil.

[bts-4120]

I thought st.louis had a decent shop. it not that far to cape

[mrsmackpaul]

Intresting. I always bumped up my idle when I was sleeping at night and needed A/C or heat. I would set it to about 700 or so....I also kept the fan on so it was always moving fresh air across the engine.

It was more to keep oil press up a little higher...I keep the fan on also to keep it from cycling on/off every few minutes be it the water temp or A/C unit telling it to do so.

This is a 3406E Cat

you sleep with the engine running I have never known anyone to do that in Australia or have I just read this wrong ????

Paul

[41chevy]

Was pretty common practice here, but now with APU's on the newer units and some places have regulations on idle time, not so much. Paul

[mrsmackpaul]

is it done to keep warm ????? or maybe stop the motor freezing I cant imagine it would be done just for the AC to stay nice and cool would it ??

[Timmyb]

Hi Paul. I wouldn't say it's common practice to idle the engine overnight, but it's not entirely uncommon. Most long haul truck here in wa will have a diesel powered aircon unit, but if not or if it broke its common to idle overnight.

Fatigue is a big deal now days so a good night sleep is a must.

[ws721]

is it done to keep warm ????? or maybe stop the motor freezing I cant imagine it would be done just for the AC to stay nice and cool would it ??

Im old school. Yes it runs when im sleeping. Heat in the wintah and A.C. in the summah. Plus in my case I live on a dead end road and if 6 vechicles go past my house all night long theres something wrong. So trying to sleep in a truck stop just plain stinks for me unless I leave it running.