AC Ice cold when moving, barely cold at idle

[BrianDye]

Noticed this problem as soon as I picked my Explorer up, but it's never really bothered me because it hasn't been this hot yet. Its probably 100+ with the sun out, temp reading about 95-98.

When I'm driving, my AC is ICE cold. Almost too cold to keep on full blast, but I am definitely not complaining about that. When I stop, or even start the car to get the AC going to cool these HOT black leather seats off, the AC is just barely cold at best. Almost as if I need to recharge it, but as soon as I start moving, ICE cold.

I watch my intake temps and coolant temp on my iPad with the DashCommand app, I'm consistently around 188-198 which seems normal, or at least that's what it's been since I bought the X.

Right now I'm parked at work, AC on, and coolant is at 196 the AC is keeping up, but the engine is idling at 1k. It's only done this when I have the AC on, not sure if it's some kind of feature? But if the RPMs dropped to the normal 650ish my AC would make me not able to sit in here.

The last few cars I've had have all had electric fans, is this just "normal" operation with an engine driven fan? If so, my e-fan conversion just jumped to the top of my priority list.

 

[Rcflyer330]

Interesting, it could be because of the condenser up by the fan. When the car is idleing there is less airflow than when its at 1k or more and the colder the refrigerent is before it get expanded to go into the car to cool the better it works. I would check the pressure. It would be best to use a manifold gauge set so you can check both the high and the low side. I do not know what each side should read but google youtube or another search engine may be able to help with that.

 

[Big Z]

Condenser fins clean?
If you idle up to around 2000rpms and observe the compressor clutch cycling frequently (maybe engaging just a few seconds at a time), you may just need a top-off of refrigerant (12 ounce can of the cheap stuff).
Otherwise, I'd do as RC said and get high and low side PSIGs from a manifold gauge set. If you do, post your values for idle and high idle PSIGs.

This might help later on:
http://www.sanden.com/objects/SANDEN_SYSTEM_DIAGNOSIS_CHART.pdf

 

[BrianDye]

Thanks for the responses guys, been a busy week, but I may get to come home from work early today, gonna try to tackle this.

Can I rent a set of these gauges at like AutoZone or something?

Ill check the compressor cycling like you mentioned today when I leave. Hopefully I just need a top off. When its cold, it freezes me out of the damn truck! Lol, but at idle, its just not great. (Sucks when I want to sit in there during my break or lunch) Plus I want to install a remote start, but without cold AC at idle, it'll defeat the purpose in the Summer.

 

[Rcflyer330]

you should be able to rent a manifold gauge.

 

[BrianDye]

Just a random thought, I wonder if there's a way to manually override the fan controller to have it on full speed (I know engine driven) but a way to basically have it spin faster while parked or something probably would also benefit in traffic jams and whatnot.

It's an engine driven fan but I believe the clutch is electronic I read?

 

[BrianDye]

Ok- so an update, as I had only used the AC a couple of times when I posted this.

Now I know better how my AC is working. What seems to happen, is I don't get very cold AC until I'm cruising for awhile. I started my X today before work, to let the AC run and it was blowing out mildly cold, at best. Kind of humid almost even.

So after I would say 2-4 miles of driving, once I got on the highway and was cruising, that's when it finally gets ice cold. It's cold once I start moving but not ice cold like it should be until I'm constantly moving. It seemed to stay very cold even once I stopped it only got a tad warmer than ice cold.

 

[jimmyznutz]

Definitely sounds like it's low a coupe pounds pressure. I bet a small can to top off the Freon would help tons.

 

[BrianDye]

Yeah I'm gonna buy one of those nicer cans with the reuseable pressure gauge on it just so I have one for future use as well.

Didn't get to come home from work today, but hopefully I will tomorrow.

 

[Big Z]

Can I rent a set of these gauges at like AutoZone or something?

I don't think a manifold gauge set is typically available as a rental tool, and I wouldn't use a 2nd-hand one without flushing it out. If you're looking for the lowest cost option to dispense refrigerant and monitor low-side pressure, you'd want something like the FJC 6036 or similar. Those trigger dispensers that come with say, the A/C Pro kits are awfully spendy for what you get (pretty sure I saw their big can with a dispenser for $60 at the store today ). A cheaper dispenser and a $4 can of plain r134a will do just fine for a top-off if you finally decide your symptoms call for it. Given just a symptom description, it would be my guess..

 

[chefduane]

You could get one of these: http://www.harborfreight.com/ac-r134a-manifold-gauge-set-60806.html Of course, its a one time buy that you many only use a few times. I just use a can of this stuff

and a simple pressure gauge that came with a different can.

 

[BrianDye]

So I got out last night finally (rented a boat over the weekend, currently suffering from the worst sunburn of my life lol) and bought one of those reuseable gauges for $20 and a can of the better looking refrigerant for $15.

Today I got out to check it and add some if needed.

I started the X (hadn't been started in 8+ hours), turned the AC on high and max AC. Also turned the rear controls on full speed and cold. Popped the hood, connected my gauge to the low side, turned the dial to adjust the "green" range to math the ambient temp, which was about 85-90, and my needle was in the red area above "55".

As I let it run, it dropped to the normal range but still on the high side of what my dial said with the temperature dialed in.

This picture was after about 5 minutes of AC on, it might have dropped a tad more but I had to go.

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My AC over the past couple of days seems to be functioning better though, getting colder quicker, not having the warm musty smell before its cold and getting ice cold before driving a few miles.

I'm stumped.

 

[jimmyznutz]

Maybe bleed off a little if it's at the high end of the green while running. Too much is just as bad as not enough on the a/c. Too high of a pressure will make the compressor run hotter and possibly not perform as it should.

 

[chefduane]

Brian, is that the gauge that is on the recharge hose or a stand-alone AC pressure checker?

 

[BrianDye]

Its a gauge on the hose, but its one of the reusable hoses, not just like one attached that you use and then toss.

Jimmy- When you say bleed off, do you mean like leave the freon can off so its just an open spout, then hit the trigger so some comes out of my system? Into a cup or something and then toss it?

 

[jimmyznutz]

Jimmy- When you say bleed off, do you mean like leave the freon can off so its just an open spout, then hit the trigger so some comes out of my system? Into a cup or something and then toss it?

Yeah, Just release a couple pounds of pressure from the system to level it out a touch. Technically your supposed to use a reclamation cylinder so your not venting the gas into the atmosphere, but I'm sure you could get away with a couple psi.

 

[Big Z]

I imagine you took your pressure at low idle? Try getting a reading at about 2000rpms, making sure the compressor is engaged when you get your value. It's normal for a full charge to put your pressure on the high side of the 'normal range' at low engine idle..and a high idle might even reveal a problem. Although it might soon be time to check the high side pressure as well if we can't figure out a problem with just 1 gauge reading. Life is so much easier with a recovery machine and a refrigerant scale
Is your condenser (the radiator, in front of the radiator) clean? Does it have a bunch of fins folded over?
Squirt some disinfectant on your cowl intake vents with the air running to help kill that musty smell. It might take a few tries to get rid of it, but that'll help it.

 

[BrianDye]

I haven't checked the condenser yet, totally forgot about that.

And I didn't mean the AC itself smelled musty, I worded it wrong. Sometimes when it's not ice cold, it's almost a bit humid feeling which leads to that smell but the smell is just the humidity I would think as it goes away as soon as the AC gets cooler (when I take off)