[vigsom]

Originally Posted by RJK

I noticed that the AC would not cool if the car was idling, nada/zero cooling. But, once the car was on the move it would cool appropriately

Thank You @RJK. Toyotas' ACs generally run trouble free for even 1.5 lakh kms till some component ages. Typically the compressor clutch coil(magnet) is the first casualty and weakens, loses the capacity to energise, and thus won't engage the compressor clutch. Result - the compressor won't engage after a few minutes of operation and eventually the cabin will feel stuffy.

However, in your case, I suspect the condenser fins are unclean. A mild pressure wash of the condenser should perk the performance up. If that doesn't work, then have the gauges hooked up to check the lo and hi side pressures, and also check operation of the compressor clutch. Toyota will do a full compressor replacement which is expensive; for these checks, I suggest taking the car to a good aftermarket AC technician.

[RJK]

Originally Posted by vigsom

Thank You @RJK. Toyotas' ACs generally run trouble free for even 1.5 lakh kms till some component ages. Typically the compressor clutch coil(magnet) is the first casualty and weakens, loses the capacity to energise, and thus won't engage the compressor clutch. Result - the compressor won't engage after a few minutes of operation and eventually the cabin will feel stuffy.

However, in your case, I suspect the condenser fins are unclean. A mild pressure wash of the condenser should perk the performance up. If that doesn't work, then have the gauges hooked up to check the lo and hi side pressures, and also check operation of the compressor clutch. Toyota will do a full compressor replacement which is expensive; for these checks, I suggest taking the car to a good aftermarket AC technician.

Thanks for the quick response, Vigsom!
Great, so I have two things to check:

1) compressor coil
2) condenser fins

Like you I also suspect the ASS will ask me to replace condenser or compressor for a high cost! I intend to take it to a local specialist as you suggested.

EDIT: Vehicle just came after being driven for an hour; checked the pipe/tubing going from compressor into the firewall, it was normal temperature, not cold at all, not even cool. So I suspect refrigerant is lacking in the system, right?

Cheers

[vigsom]

Originally Posted by RJK

checked the pipe/tubing going from compressor into the firewall, it was normal temperature, not cold at all, not even cool

There will be 2 tubes at the firewall - one with a smaller diameter (high side) which is the compressor discharge and one with a larger dia (low side), which is is the compressor suction.

With the compressor in operation, the low side tubing should be sweating and should feel like a chilled can of beverage. If the compressor is off, obviously the line will be at normal temperature. If the low side line feels like normal temperature with no sweating even with the compressor engaged, then I'd suspect that the refrigerant charge is low.

This is a video of the compressor clutch engaging and disengaging in a 2012 Innova. The compressor is right at the top, just behind the coolant expansion tank.

https://youtube.com/watch?v=C6O4utZkDrg?feature=share

[RJK]

Originally Posted by vigsom

There will be 2 tubes at the firewall - one with a smaller diameter (high side) which is the compressor discharge and one with a larger dia (low side), which is is the compressor suction.

With the compressor in operation, the low side tubing should be sweating and should feel like a chilled can of beverage. If the compressor is off, obviously the line will be at normal temperature. If the low side line feels like normal temperature with no sweating even with the compressor engaged, then I'd suspect that the refrigerant charge is low.

https://Youtube.com/watch?v=C6O4utZkDrg?feature=share

Yes, I did see two tubes, both were room temperature. The car and AC was off but it was barely 2 mins after the car was turned off. My suspicion is if it must feel like a chilled beverage can, it can’t/shouldn’t warm up to room temperature within 2 minutes, right? Especially after having the AC on for an hour. Nonetheless, I will double check with the car running tomorrow.

Cheers!

[RJK]

Originally Posted by vigsom

There will be 2 tubes at the firewall - one with a smaller diameter (high side) which is the compressor discharge and one with a larger dia (low side), which is is the compressor suction.

With the compressor in operation, the low side tubing should be sweating and should feel like a chilled can of beverage. If the compressor is off, obviously the line will be at normal temperature. If the low side line feels like normal temperature with no sweating even with the compressor engaged, then I'd suspect that the refrigerant charge is low.

This is a video of the compressor clutch engaging and disengaging in a 2012 Innova. The compressor is right at the top, just behind the coolant expansion tank.

https://Youtube.com/watch?v=C6O4utZkDrg?feature=share

Update:

Took the vehicle to AC shop yesterday. Workshop guy checked compressor, found ok and immediately said low refrigerant. Gave me 2 options:

1) Top up gas for 1500 bucks & be on my way
2) Do a comprehensive service where they open up both the evaporators (cooling coil), remove condenser for cleaning, clean up the blower, water clean the radiator with mild pressure. All this for 4500 which they later agreed to do for 3700.

I opted for comprehensive job since the entire system was never opened and I could visibly see a lot, A LOT of dirt lodged in the fins of condenser.

So they started the job, took a good 4 hours to finish. While testing both the evaporators individually, I saw a leak in the front evaporator. I was told it’s not repairable and have to replace. They charged me 6500 for a new one, Denso make, which I found out before hand sells for about 4800-5100 price. Didn’t have much choice than pay up because the car was open and no way for me to procure on my own. Bit the bullet and paid up the additional money.

In total, it costed me 10k for the entire job but the AC is cooling fantastically! The workshop guys mentioned that lodged dirt is the main culprit for failure of the evaporator and that if I periodically device ie every 1.5-2yrs, evaporator would have lasted longer. The way I saw it is, in 7.3 months of ownership, 1 part failure is acceptable. As such the 2 services would’ve costed me more than the cost of evaporator.

All these are after market prices. Toyota dealer (Madhuban Toyota) said I would need to leave the car for 2 days for the job and a leaking evaporator would cost 13k to replace. Additional would be labour cost, so I estimate total cost to be atleast 16-17k inclusive of labour and taxes. I’m not looking to keep the vehicle for more than 2yrs tops, so longer reliability is not concern for me. In any case, I have replaced with a Denso original part.

Hopefully this helps someone else as well.

Thanks Vigsom for your assistance.

Cheers

[thomvee]

My 2017 Duster RXS CVT petrol has some issue with the AC. When you start and short drives it works perfectly fine. On long drives on hot days the AC stops cooling. Fan still works. I have taken it to two separate Renault showrooms. They seem to have no clue and cant figure out the issue. They have reset the AC and changed the vents etc. Both places said it has been fixed but it happens again on the next long trip. It seems to happen only after a 100-200KM drive when the sun is out. Anyone else has faced similar issues or has any idea on it?

[Rocketscience]

Originally Posted by vigsom

Introduction

Air-conditioning has become integral to the lives of almost all of us, while at home, while at work and while in the car.

Extremely well written, researched thread. Kudos.
My question is regarding the Variable compressor you mentioned that Creta, i20 and all use.
If they are on all the time, what happens when you turn off the AC? Since they have no clutch to disengage?
Also, in my Creta since it was new (It is more than 5 years old now), the Compressor cuts off whenever I floor the car, even if I don't redline it (a futile exercise in a diesel), so whenever I do that the cooling stops briefly and then resumes the moment i'am done with revving and start driving normally. Why would that be or is my generation of Creta not using this type of compressor?

[shashanka]

Very well-written and informative thread, Vigsom. And the additional inputs from members (Jeroen and others) is also helpful. The variable delivery, axial piston compressor/pump (or swash plate type) is indeed a very efficient unit and widely used in industrial hydraulic applications. But the swash plate control linkage is the weak point! Losing a small quantity of hydraulic oil due to seal leakage is one thing, but when it comes to losing & releasing refrigerant gas (even the green enviro-friendly gases now in uses) into the atmosphere - that becomes a serious issue indeed.

I remember the curses the engine room crew would heap on the equipment everytime the unit had to be dismantled for replacing seals and the resultant mess from the draining hydraulic oil in the ship's steering compartment.

Thanks again for a very useful thread.

[WheelD]

Originally Posted by Raghu M

This is a great thread. I have had a problem with my AC just before trying to sell it off. I thought, it would be prudent to get the repair done and then hand over my car so that the buyer has a great experience with car. The AC stopped cooling and turned out the radiator fan was also gone. The AC works guy first told me that will check the AC gas and then if there is a leak, when the gas and leak status are confirmed, he will take further action. He was patient enough to clarify all my doubts. He checked the gas and found that it was gone, then he checked for a leak. Luckily there was no leak, the process to check the leak took around 45 minutes. After that they refilled gas and replaced the radiator fan. It was working like magic again.

Can you help with where you got your AC checked. I want to get mine done too. Thanks.

[Jeroen]

There is another weak point in the variable delivery AC compressors, as various manufacturers have found out. As in these applications the compressors runs constantly, even though it might not be providing any cooling. That also means the pistons get less lubrication. In traditional AC compressor installation the system is filled with the appropriate quantity of compressor oil. The oil circulates throughout the system with the refrigerant. But with these variable AC compressors, when idling away, sufficient lubrication becomes a problem.

So a couple of years manufacturers started adding clutches to these variable compressors too. When the loading of the compressor is down to zero, the clutch disengages and all of the compressor rotating parts come to a halt. As soon as it needs to provide cooling, the clutch engages and the normal variable regulation kicks back in.

Learned this from my new AC Specialist friend Jack who helped me out on re-charging my Jeep Cherokee after I had replaced the AC evaporator.

You can read about that adventure here:

https://www.team-bhp.com/forum/diy-d...ml#post5307858

No sooner I had fixed my Jeeps AC, the AC on my wife’s 2015 Ford Fiesta packed up. Jack helped me diagnose it as a leaking condensor. The new one has arrived today. We will be replacing it sometime in the next few weeks. Should be fun, the whole front of the Fiesta needs to come off. Watch my fiddling thread.

Jeroen

[vigsom]

Thank You Rocketscience, embee and shashanka Sir

Originally Posted by Rocketscience

My question is regarding the Variable compressor you mentioned that Creta, i20 and all use.
If they are on all the time, what happens when you turn off the AC? Since they have no clutch to disengage?
Also, in my Creta since it was new (It is more than 5 years old now), the Compressor cuts off whenever I floor the car, even if I don't redline it (a futile exercise in a diesel), so whenever I do that the cooling stops briefly and then resumes the moment i'am done with revving and start driving normally

In the variable displacement compressor, the pulley and the shaft will always be running, but the loading will vary based on opening of the ECV. Here, even at the full close position of the ECV, there will be a bare minimum load on the compressor. The last two videos on post #5 of this thread will help you understand how this works. Please watch 1:50 onwards in the attached video.

https://youtu.be/ItvfKv0iRPY

Hyundai Creta compressor running


Hyundai Creta Compressor ECV wiring harness

Originally Posted by shashanka

But the swash plate control linkage is the weak point!

Agree, Sir. To do away with failed linkages, leaking seals and the like, I always wondered why they didn't introduce vapor absorption refrigeration systems in cars, then realised that steam generation was an issue. Motor driven hermetically sealed compressors like in refrigerators and domestic ACs would have been better but here again, it would be impossible to generate enough power to drive a motor of high kW rating.

[Rocketscience]

Originally Posted by vigsom

Thank You Rocketscience, embee and shashanka Sir

This sounds like a great tech and needs to be advertised, it is somewhat like Inverter compressors in home which are all the rage these days, this can provide better cooling consistency and lesser fuel consumption, but then being on all the time even when not needed must have some impact on FE too, where does that cooled air go though? Is it just discarded?

[shashanka]

Originally Posted by vigsom

.......Agree, Sir. To do away with failed linkages, leaking seals and the like, I always wondered why they didn't introduce vapor absorption refrigeration systems in cars.......

What I gathered from the net is that the absorption system had been introduced in RVs in the US. I also understand that this type of refrigeration system requires a carefully levelled installation since gravity plays an important part in the circulation of the refrigerant. Otherwise it would be the ideal solution - no moving parts at all and it only requires a heat source to start the system! Also, since ammonia was the original refrigerant used in this system (I dont know if some other fluid is used today), a leakage would be toxic!

Another interesting point has been raised by Rocketscience - that of the continuous running of the variable delivery pump even under no load. Normally, the ECV (or the Thermostatic Expansion Valve - or TEV) regulates flow of refrigerant through the evaporator, and this regulation depends on the degree of superheat at evaporator outlet (usually 5 degrees of superheat), to prevent liquid knock at the compressor. So, once the ECV has come to the superheat setting, a small amount of gas will keep passing through the evaporator and on to the compressor inlet, and the compressor will keep running, since the compressor shuts down only on zero flow through of gas. Normally on other reefer installations, this compressor shut down is activated by a pressostat, sensing the gas pressure at evaporator outlet. This pressostat provides a signal to a solenoid valve on the return/inlet line to the compressor, thus shutting off gas flow completely, which shuts down thecompressor.

My guess is that (in a car AC system), the cabin temperature via a thermostat would deactivate (as pointed out by Jeroen in his post on this point) the electro-magnet clutch, thus decoupling the compressor and stopping it.

I look forward to any corrections from members, in case my understanding/assumption is incorrect.

[Raghu M]

Originally Posted by WheelD

Can you help with where you got your AC checked. I want to get mine done too. Thanks.

It's on Road no.1 KPHB. I can't recall the name correctly but the guy is right opposite Prime Hospitals. He does a decent job, it's a small shop.

[Captain Slow]

My Local AC guy tried to top up the AC Gas - Not sure what he did but now whenever the AC is switched on (compressor) the Fan runs at 100% speed!
Earlier the Fan used to run only when the engine started to heat up, now the fan runs the moment the Compressor is switched on.
The cooling is also not very good after this guy tried to "Play with the AC System".

Any Suggestions?