A/C only blows while driving

I have a question, on my 12 tacoma the ac only cools while it’s driving however when I stop and the truck is on idle it stops cooling. Has anyone had this problem? My Freon level is topped off and my compressor kicks in. I heard it could be the fan clutch but it doesn’t have a winning noise.

Thanks
Arlen

 

Mine blows very cold on hwy and will warm up considerably if I get caught in a lengthy stretch of bumper-to-bumper stop-n-go freeway traffic. I cleaned the condenser yesterday with the front grille off. I doubt this was the issue, but did so anyway.
Local dealer mistakenly replaced an a/c compressor last summer. Refrigerant charge was evacuated before replacement. I suspect what was taken out was not replaced in it's entirety. 99% of my driving is hwy. so I'm not too suffering too much. These newer R134A systems use less refrigerant than their predecessors, so I may be off just a few ozs. I never noticed this problem until after the dealer visit.
I'll soon grab a set of R134A gauges and figure out if an insufficient charge is the issue.

You say your "Freon" level is topped off. Were gauges used by someone who understands how to use them to ensure sufficient charge?

 

A buddy of mine connected his ac gauge and we saw the Freon levels where ok.

 

It would be interesting to know what the low/high side pressure readings were and what the ambient temperature was when the gauges were hooked up.

 

Sounds like the fan is weak. What are your pressure readings and how hot is the ambient air temp? How cold is it out of the vents?

 

Not trying to jump the thread, but I'm beginning to think this may be my issue. Again, I need to first verify the charge. I was looking at the fan speed the other day with a really warmed up and idling 4.0L motor. I just wasn't seeing/feeling much in the way of air flow. I have a 27 yr. old MB gas car whose viscous fan sounds like a lion when it engages. I can sit in the car with the drivers side door open and feel a strong flow of air. I've never experienced any sort of viscous engagement by my '15 4.0L Tacoma. Not sure just how strong an engagement I should be experiencing in this truck.

 

A set of manifold gauges (2) is needed. A suicide hose with just a low side gauge is not very helpful.

A hi side reading that is too hi (over 300-350) could indicate a lack of heat exchange at the condensor (like a faulty viscous clutch)

 

For the low it was reading about 40 psi and the high was about 281 psi with a ambient temp of 90

 

Thanks.

 

Thats pretty good. Your system is likely operating as well as it can

 

But you can really tell the difference from idle to when your moving. It didnt do that when I first bought it.

 

It could still be undercharged. When you're cruising the engine rpms are higher so the higher pumping rate can offset a low charge. Sometimes in order to be sure of charge level you have to recover all the refrigerant with a service machine and then add the specified amount

 

The real problem here is that no air is passing through your condenser when your truck is not moving.
These trucks (and most trucks or other RWD vehicles with mechanical clutch fans) have fans that engage intermittently. Other cars (including all FWD cars) have an electric fan that can be commanded to turn on whenever, for how ever long. This is why a FWD car will have stellar AC when idling, but a truck will not. There's just nothing pulling air through the condenser for heat transfer.
This is why your AC works while you are moving at highway speeds and shoving air through.

To help remedy this, you could install an aftermarket electric fan setup. Here's a pretty good thread I came across
https://www.tacomaworld.com/threads/a-c-condenser-fan.239576/

This guy even wires it in to the fusebox and makes it look factory.

 

If his 281 psi was higher, maybe over 350 I would consider supplemental cooling. 281 is right in the range..

If he slapped an electric fan in there, that 281 would drop, the difference across the orifice would be less and a/c performance would be less

 

I’ve seen an undercharged system give the same readings with a bad fan clutch before. No heat exchanged will cause high pressure readings on an undercharged system.

 

Are you able to stick a thermometer into your vents so you can measure the temp differences while driving and while idle?

 

Put in N and rev it to 2000 rpm, if not colder after then fan clutch might be an issue or evap is clogged with junk

also check your cabin filter

mine is never super cold when at idle, once moving it does get colder and its been that way on all my trucks with a fan clutch since 88

 

Does the flow change when Recirc button is pressed versus Fresh air intake?

 

Not really. The difference is that on recirc the system is removing heat from already partially cooled air. Like air that's already been blown across the evaporated and had some of the heat removed.

 

I disagree. On Recirc the cabin air is recirculated - no outside air coming into the HVAC system. When Recirc is off, and at highway speed, fresh outside air under pressure at the windshield base is flowing higher pressure air into the cabin. I have much higher air flow out all vents with Recirc off as no high pressure air flows in from the windshield base.
It may not be as cold, but it is a higher volume of air flow, which is what the OP stated was the difference between at highway speed versus stopped at idle or slow in heavy traffic.