A/C compressor sticky valve

[Auri 7]

Hi all,

I get the occasional aircon problem, where I can't adjust my temperatures.

I can feel mixed cold and warmish air come out of the vents.

Most of the time, switching off the engine and restarting it will fix it, and I get cold air again.

The mechanic reckons, it's a sticky valve in the a/c compressor.

Has anyone had any experience with this problem ?
Would it indeed need a new compressor to fix this ?

Happy for any help,
thanks

(Aurion 2010 Touring)

[trentmeyer23]

If the compressor clutch is slipping, this may also be a symptom.

[Auri 7]

1 hour ago, trentmeyer23 said:

If the compressor clutch is slipping, this may also be a symptom.

Thanks for your reply !

Switching A/C off with the button while driving makes no difference.

When I turn the dials, I can actually hear the cogs of the flaps turning, but it won't do any good either.

When the fault condition is present, only stopping the engine, and restarting helps.

If it was the clutch, would it not (sometimes) come good with the electrical on/off button ?

I'll look into this a bit more tomorrow though (listening to the clutch).

Cheers

[trentmeyer23]

If it is slipping bad enough it may not engage at speed.

[Auri 7]

12 hours ago, trentmeyer23 said:

If it is slipping bad enough it may not engage at speed.

Thanks, Trent,

I'll check it out.

[Auri 7]

I should've updated this moons ago, in case someone is looking at something similar:

I was able to free the sticky valve by just altering the temperature settings a multiple number of times, making the valve re-position itself more often.

 

Background:

I always drive with A/C ON. I used it for years on the same setting: 23 degrees, summer and winter alike. It worked well for me, up until the problem started.

My solution: I started to manually adjust the dials to higher and lower values. It took some time, but freed it up eventually.

So maybe it's a good thing to do this more often from early on.

Cheers

Edited December 4, 2016 by Auri 7

[Tony Prodigy]

The valve you're talking about, If I understand you correctly is the butterfly valve inside the A/C ducts. If these jam up, sure you will get a mix of hot and cold air or one or the other.

Switching off the A/C button only isolates the compressor motor. I can understand why it does rectify itself after re starting the car. You de energize the system which can reset those other components.

When you are talking about the A/C compressor, this is strictly mechanical. It's the pump inside the engine bay that pumps the R134a refrigerant to the heat exchanger (Evaporator coil) inside you cabin under the dash. If the compressor had a "sticky" valve, then it will cease to pump refrigerant. Did the mechanic do a pressure check on the systems running pressures ? This will usually determine a fault with the compressor.

I'm not sure what type of compressor is in your Aurion, but most modern cars have variable displacement compressors which allows a bypass of refrigerant when it isn't needed to help reduces drag on the engine and save fuel. There is a control valve that usually fails on these types of compressors and can be fixed pretty easily without having to replace the entire unit.

On the other side of things...

There are two cores inside the dash. One for heat, which is governed by your cars cooling system, and one for cooling, which is governed by the  A/C compressor mounted and driven by the engine.

When you select full cold or close to this, the damper (butterfly valve) will close fully on the heater core side and only allow the delivery of cold air from the A/C evaporator side.

Automotive A/Cs don't have reverse cycle, so it needs this kind of actuation in the ducting, to bypass either the heater core or the A/C evap. 

When you select a mid temperature like 23 degrees, the damper will open almost to the full position on the A/C evaporator side and very partially on the heater core side to allow the mixed air be delivered to satisfy the 23 degrees you've requested. The higher you set the temp, the more the heater damper will open. The colder you set the temp, the more the heater damper will close and call for fully open on the Evap side.

So it's not a bad idea to occasionally cycle the actuator motors on both sides to stop them from "sticking" so to speak.

A good reminder for everyone I reckon. I'll have to remember to do this to mine too.

Cheers Tony 

Edited December 4, 2016 by Tony Prodigy
Typo

[Auri 7]

Thanks, Tony,

great post with lots of info !

 

[Tony Prodigy]

Happy to oblige where I can.

Thank you 

[campbeam]

Fortunate enough to have previously read the post about sticking valve and A/C Temperature setting.

I usually have the temperature setting on maximum cold and just change the fan speed and airflow direction.

We have had a few 34 degree days in Brisbane so driving with maximum cold setting and full fan speed. After lunch, I had just turned onto the local highway and accelerated up to 80kph speed limit when I heard something unusual then the cabin was filled with an unbearable air pressure related resonating noise.This noise went away when the window was lowered but returned when the window was raised. Turning off the air-conditioner made no difference. Later, I checked under the car and noticed water dripping from a rubber tube,condensation from using the air-con. After checking the engine bay, wheels and the exhaust, I then went for a short test drive but no problems.

A few hours later when accelerating onto the highway, I heard a clicking noise coming from the dash near the central air vents. While driving and changing the air-conditioning controls by touch, either myself or my passenger accidentally changed the temperature setting. All solved; no more resonating noises and clicking noise gone. 

[trentmeyer23]

The water is condensation from the evaporator, which is part of the HVAC unit.

The hose is a drain hose from this and would be far more concerning if it wasn't dripping on hot humid days. They often block up from leaves and other debris and cause wet carpets/musky smells.

The clicking could have been one of the control servos behind the dash.

[campbeam]

26 minutes ago, trentmeyer23 said:

The clicking could have been one of the control servos behind the dash.

Agree. Air-conditioning system was re-gassed in March 2016 and I have had the temperature setting on max. cold since then.

Quite happy it was just this instead of a wheel bearing, the A/C Compressor or an engine belt etc.

[Tony Prodigy]

11 hours ago, campbeam said:

Agree. Air-conditioning system was re-gassed in March 2016 and I have had the temperature setting on max. cold since then.

Quite happy it was just this instead of a wheel bearing, the A/C Compressor or an engine belt etc.

Hey mate,

just wondering why you had the A/C re gassed ?

Did you have a gas leak or mechanical issues ?

[campbeam]

I bought my 2006 Aurion from a wholesaler via eBay about 2 years ago and then had it sitting for some months. Although service records were provided, no exactly filled with confidence that it had been serviced by a non-Toyota dealership under some extended warranty plan.

Air-conditioning was ok but I thought that it could be colder. Decided to get the air-conditioning system checked and re-gassed before going on holidays. Mobile specialist checked the system for leaks; none, before re-gassing the system. I asked about whether any parts needed to be replaced; none, all ok.

What he did mention was that the limitation of the 500ml capacity of the air-conditioning system [compared to other vehicles] and to use the recirculating airflow for better effect that having the system trying to cool hotter air from outside.

[Tony Prodigy]

3 hours ago, campbeam said:

What he did mention was that the limitation of the 500ml capacity of the air-conditioning system [compared to other vehicles] and to use the recirculating airflow for better effect that having the system trying to cool hotter air from outside.

The capacity of the A/C is well and truly adequate. That is, if you are referring to it's ability to condition the space efficiently.

If the system had some tweaking, ie, regas after an issue or someone thought to add more gas to make it "colder".... then I would be suspicious.

If you over the charge the system is it as bad as being under charged.

I don't have the car here to check how many grams of r134a, but i'm guessing around half a kilo.

I would never use the outside air function on a hot day as it does make the system work ever so harder.

The amount of moisture in the air during summer is unbelievable.

Keep it on recirculate and the A/C should pull down within 5 minutes or so.

Toyota Air is probably the best on the market. My Aurion absolutely kills it in summer, no problem.