Air conditioning experts, please step in....

[MajorCavalry]

Hi all,

Having an intermittent problem with the air conditioning in my 2012 Acura TL.

Can work fine for days then suddenly will stop cooling. The air starts to get warmer through the vents. Still blowing strong. Sometimes turning off the air conditioner and then turning it back on results in return of cooling. When this happened the last time, I turned the automatic temperature control up to 70 from 66 where it was and cooling started working again.

About two weeks ago the compressor clutch relay was replaced at the dealer and for two weeks there were no problems. Dissection of the old relay showed pitted and burned contacts. The dealer had run diagnostics and no electronic faults were found. Refrigerant pressures/levels were OK

So, what are your thoughts?
1. Defective relay? seems unlikely. Used and original part.
2. Internal temperature sensor malfunction
3. Outside ambient temperature sensor malfunction
4. Something more expensive.

 

[mk378]

First, when it is not cooling, pull over leaving the engine and A/C on and look under the hood to confirm that the clutch is indeed not engaged. If the clutch is engaged but no cold air the problem is not related to the relay etc.

Pull the relay out of the box and look for melted or burned contact points in the socket. If that happened you should replace the box as well as the relay again.

Another common problem is the air gap in the clutch is too wide, this causes intermittent engagement even though the clutch has power it doesn't pull in. This is prone to work at the start of each trip, but then stop as the clutch coil heats up (a hot coil develops less magnetic force). Usually this can be adjusted without buying anything, by taking shim washers out.

 

[punisher]

mk378 covered it. Air still blowing strong eliminates frozen up evap core. Safety warning- If the clutch is not engaging, and it is accessible, you can use a screwdriver, or similar object to ck for a magnetic field. Sometimes, actually most times, when you tap on the clutch face it will engage if the field is weak. Safety warning because it will launch a screwdriver through things if it gets caught in the clutch when it engages.

Does a scan tool pick up an "AC demand" signal to the PCM when the AC is on?

 

[MajorCavalry]

Originally Posted By: punisher


Does a scan tool pick up an "AC demand" signal to the PCM when the AC is on?


I cannot answer this question as the mechanic did the diagnostics. I really appreciate the input from all. Great idea about pulling over and seeing if the compressor clutch is engaging. Little hesitant about the screw driver idea. Hate to see it launch LOL

 

[sleddriver]

Originally Posted By: MajorCavalry
Having an intermittent problem with the air conditioning in my 2012 Acura TL.

Can work fine for days then suddenly will stop cooling. The air starts to get warmer through the vents. Still blowing strong. Sometimes turning off the air conditioner and then turning it back on results in return of cooling. When this happened the last time, I turned the automatic temperature control up to 70 from 66 where it was and cooling started working again.

Since you have electronic climate control, it could be the controller itself. It may intermittently be "going wobbly". You may also have dirty/dusty/hair-covered temp sensors that the ECC relies on, giving it false information.

MK378 covered the rest.

 

[MajorCavalry]

Originally Posted By: sleddriver
Originally Posted By: MajorCavalry
Having an intermittent problem with the air conditioning in my 2012 Acura TL.

Can work fine for days then suddenly will stop cooling. The air starts to get warmer through the vents. Still blowing strong. Sometimes turning off the air conditioner and then turning it back on results in return of cooling. When this happened the last time, I turned the automatic temperature control up to 70 from 66 where it was and cooling started working again.

Since you have electronic climate control, it could be the controller itself. It may intermittently be "going wobbly". You may also have dirty/dusty/hair-covered temp sensors that the ECC relies on, giving it false information.

MK378 covered the rest.


Where is the temperature sensor located? Would like to clean or replace.

 

[Kansas_Ron]

Could it be a dirty cabin air filter?

 

[MajorCavalry]

Cabin air filter was recently changed.

Also noticed fan speed is erratic. Picks up speed, slows down like it is not sure what speed to be at. Does this clue add any information.

I took some canned compressed air and gently tried to clean the cabin temperature sensor.

 

[Vikas]

does it do the same if you set it at max ac aka turned it all the way?

 

[vssjim]

We put a lot of relays in Honda cars like they did for yours some times they wont engage at all or stick on and wont shut off and kill battery. The dealer probably on a guess just put in a relay which it would have needed anyway but we also see just as many clutch coils. We put in a lot of coils when available or compressors when clutches are not. Just check for power going to clutch wire and that is probably problem you are looking for. The only other problem is too large a gap on clutch which is not too hard to adjust just zip off nut and clutch drive plate as there are shims on shaft or up in drive plate. Just a few thousands gap when free wheeling is all that is needed. Usually the gap is too large when it wont reengage once hot but always works at the start of a trip. If it is the clutch coil failing it will get worse until it quits working all together. If the cooling fans on radiator at all times and pulling relay out and in you here it clicking you can probably guess it is a clutch coil or gap adjustment because on some cars getting wire on the when working on the ground is tight but on other models not too bad. If the gap is too large you can also really carefully pry against clutch with a long and rub against clutch and see if it pulls in but you must make sure stick is on correct side so it rubs when rotating not causing any injuries to you.

 

[MajorCavalry]

Originally Posted By: Vikas
does it do the same if you set it at max ac aka turned it all the way?


When it is not working, putting it on AC max with manual fan does not eliminate the problem other than the erratic fan.

 

[Kestas]

Perhaps bad solder connections on the climate control unit?

 

[Vikas]

Usually on a Honda, A/C relay and the heat-sink'd resistor on the blower controller are two of the common failure items. But the first thing to check would be if the compressor is turning when it starts throwing hot air

 

[vssjim]

T update this thread I put to clutch with coil assemblies on Hondas this week one would come and go the other one dead. On both cars blowers worked fine and cooling fans would come on and power to ac clutch but coil open and would not work. Both had proper charge which also by the cooling fans and blower working tells you its trying to engage clutch so check for power at compressor wire if it has power you need a clutch or compressor

 

[MajorCavalry]

Update.

Acura tech drove the car until the problem developed. Diagnosis revealed failed high pressure sensor. Part on order. Will require evacuation and recharge to replace. Hope this works.