[Alphard]

Hi Team,

I am writing to you to seek help with a problem that I am facing with my 2010 Toyota Innova 2.5V D-4D.

Problem Statement
My Car has an automatic AC and the AC normally works well and cools the entire car cabin effectively. However sometimes, the AC starts heating the cabin instead of cooling the ambient air - this issue happens intermittently.

Problem Description
If I switch on the AC, sometimes it will start cooling normally and sometimes it will start heating the cabin.

When the AC starts cooling, the AC will keep cooling regardless of how many KMs or Hours the vehicle is driven.However if the vehicle is stopped and then restarted, there is no guarantee that the AC will resume cooling or start heating the cabin instead.

If the AC starts heating the cabin, the AC will keep heating the cabin regardless of what temperature is set on the AC control panel.Once the AC starts heating, it works completely opposite of what it is supposed to do i.e. if I lower the temperature on AC control panel, it will start blowing more hot air in the cabin.

When I start the vehicle, the problem with AC is indicated by the AC control panel going dead and blinking of the AC defogger light (i.e. the small amber coloured LED on the defogger button on the AC control panel) for about 20 -25 seconds. Once the AC defogger lamp stops blinking, the AC control panel starts - however the AC may or may not cool the cabin.Moreover, this problem seems to affect only the front AC air vents on the dashboard - the rear AC vents keep cooling the cabin.

I have checked online and even visited Toyota Service Centre 4 times in the past 2 -3 months to get this issue addressed. Initially they had re-programmed the AC control panel and told me that the problem has been resolved. However, despite the AC control panel re-programming, the problem had re-occurred and I have been visiting them repeatedly to get the issue resolved.

In one of my recent visits to the service centre (Aug 1st week), my vehicle was kept with the Toyota Service Centre for 3 days to enable them to properly diagnose and fix the issue.They had replaced the AC control panel giving me an assurance that the problem has been solved. However despite their best efforts, the problem reoccured with the vehicle being driven for less than 100 km since taking delivery of the vehicle.

After the problem reoccurred, a team from Toyota Service Centre was sent to my home to check the issue. During their visit to my home, we took the vehicle for trial run and a different issue with AC control panel cropped up - the AC panel would keep turning on /off, display random numbers and become unresponsive during the drive. The Team took the vehicle with them so as to attend to the issue. They investigated the issue and I was informed that it was due to some loose electrical connection. The vehicle was with Toyota Service centre for 4 days and now the original AC problem had reoccurred with the vehicle being driven for less than 100 kms.

I think significant time (i.e. total 8 days on 4 occasions) and quite some money (~= INR 12000) has been spent on this issue - however the issue still persists.
The staff at Toyota Service Centre has been helpful, sensitive and responsive to my concerns however now I am at my wits end trying to understand how to get the problem fixed.

I have raised a Grievance with Toyota India last week however they have just routed me back to same Toyota Service Centre. Given the past experience, I am not sure whether taking up this issue with the same Toyota Service centre will do any good.

I would like the our members to guide me based on their rich experience and technical knowledge and advise me on the way forward.

Thanks & Regards
Alphard

[pkulkarni.2106]

My understanding of car AC systems is somewhat limited, but here are my two cents:

Back in the past, car AC systems relied on manual sliders to toggle between hot and cold air. Depending on the chosen setting, air would be sourced from either the heater core or the AC unit.

Considering that the Toyota technicians have already replaced and reprogrammed the control panel, I would speculate that the issue might be with the valve or door responsible for regulating the transition between hot and cold air.

[Jeroen]

If the Toyota mechanics start swapping electronic parts or reprogram stuff I would hope they did a thorough analysis. Which means hooking the car up to a proper OBD analyser that can access the AC system. Ask them for the error codes. If they don’t know, or say it can’t be tested, you know they are lying.

Reprogramming the computer is unlikely to have been the problem in the first place.

I believe this problem to be more likely related to one of the sensors, flaps and or valves that control the air flow. Not sure how they operate on this Toyota, pneumatic (vacuum) or electrically.

Where as the electronic problems can usually be diagnosed easily, if you have access to a good OBD analyser, everything else is a lot more complicated. It also means in most cases taking the whole dashboard apart! Ask me how I know!

So you really need to find a very competent mechanic and it might take quite a few hours to find the problem.

Good luck

Jeroen

[shikh_oberoi]

Please check if the outside temperature sensor is working correctly. How much temperatures does the car shows on the screen?

Ac mechanic damaged my verna's outside temperature sensor and the car was blowing hot air. The ac panel showed a temperature of 8*C. He fixed it and the temperature changed to 38*C and it started cooling again.

[Jeroen]

Originally Posted by shikh_oberoi

Please check if the outside temperature sensor is working correctly. How much temperatures does the car shows on the screen?
.

Unlikely due to this symptom

Moreover, this problem seems to affect only the front AC air vents on the dashboard - the rear AC vents keep cooling the cabin.

If the outside temperature sensor was not working correctly it would affect the whole system. Not just the front AC air vents.

Jeroen

[NomadSK]

Hey, seems I had almost the similar problem in my vehicle, check post#84

https://www.team-bhp.com/forum/techn...ml#post5555886 (Air-con: Center vents throwing out warmer air than side vents?)


The local FnG guy went below the dashboard on the passengers footwell and corrected the blender door actuators position which was stuck in its position. That’s what he told me, I couldn’t get the exact troubleshooting scenario because of the language barrier and while he was fixing (I thought it will take some considerable time) I went to get some water and while I came back he said, it’s fixed. At that point I was a bit skeptical. One tend to trust more on service Centre than a local mechanic.

Afterwards, I tested it with few scenarios (auto/manual, heating/cooling), it’s been few months now and it’s working fine. I couldn’t update the thread, since I didn’t exactly knew what he did in those few minutes. He even didn’t charge me for this, since he had earlier taken the payment for OBD scanning.

So I guess it’s all about correct troubleshooting with an OBD scanner and the correct fault finding. Don’t let anyone implement hit and trial method. At the Toyota service centre they told me, that they will have to pull down the whole dashboard only for diagnosis

[dhanushs]

The heat in the hot air is from the engine coolant and there is a valve that controls it.

Most likely in your case that valve is a problem and it brings in hot coolant even when not asked for. You have to go to a dedicated Car AC Mechanic to solve the issue.

I had a similar problem in my Ford iKon years back and the jugaad done was to bypass the coolant completely. i.e. I only get cold air.

[matchvan]

Originally Posted by dhanushs

The heat in the hot air is from the engine coolant and there is a valve that controls it.

I had a similar problem in my Ford iKon years back and the jugaad done was to bypass the coolant completely. i.e. I only get cold air.

Greetings,

Even I had a similar problem in my SX4 where the coolant would leak under the dash near the steering column when the temperature was set to heat the cabin, which ofcourse we folks down south don't need!

My FNG simply disconnected and bypassed the the coolant hose that carries warm coolant to the blower unit.

Pardon me if my terminology is wrong.
But a FNG or a local AC technician would take care of the heating problem alone.

Drive Safe.

[Shitij]

A close family member has the same problem in his Innova Crysta.

His problem used to come up whenever he set the temperature to more than 25 for heating or when he switched on the defogger. When he set the temp back to cooling or switched off the defogger, hot air used to come out of the vents and make the situation very bad and embarrassing. Since the issue didn't happen every time, it could be replicated in front of ASC once or twice and a proper resolution couldn't be reached.

Once he was stuck in a bad situation where he just started a long trip back home and the system was stuck on heating and soon he entered plains where it was around 40 degrees. He somehow reached home and went to the Service center next day where after a lot of investigation they concluded the alternator (if i'm not wrong) which switched the heating back to cold behind the control panel has gone bad and it is approx 20-25k including labor.

The solution he found was he removed that part altogether, yes the car doesn't turn on heating but he doesn't require heating 95% of the time anyway. Now even if he sets the temperature to 30 degrees, all he gets is normal room temp air.

[bravo82in]

I can share my experience with a similar issue. After every car wash or after rains AC would blow hot air at whatever temperature you set it with a warning on MID ‘Ice expected’ The vehicle in question was Tata Aria. The issue was traced down to a faulty external temperature sensor which would send outside temp reading as -40 degrees C to the AC.

Maybe you can try changing the external and/ or internal temperature sensor.

Hope this helps

Regards
Bravo

[sasta_rider]

A lot of Innova owners I have interacted with, have reported the AC cooling/abnormal behavioral issues. Even in online forums, including TeamBHP, AC issues of Innova have been pointed out.

In my 2011 Innova (which has manual AC control), the cooling was bare minimum. There are two ASC near to my home: United Toyota, Padil and Amana Toyota, Kasaragod. As I had been to Mangaluru for some work, I decided why not point this issue at United Toyota so that they can come up with a solution.

A SA came, without even trying to recreate the problem, informed that they will have to refill the coolant and check. I said OK, they filled the coolant and handed over the vehicle, AC cooling had come back to normal. This stayed for a week, followed by the same poor cooling. Since I had done the coolant refill at Mangaluru, decided to take it all the way there for another round of diagnosis. This time, a different SA (previous SA was on leave), informed me that they will have to remove the dashboard, check for any leaks and only then can conclude why the cooling is almost nill. I agreed, kept the vehicle for a day and left to my relatives place nearby. Next day, when I went to pick the vehicle, the bill was hefty, which as expected. This included the labour to remove and fix the dashboard along with refilling of coolant.

A week passed, again the same issue showed up. This time, I planned to visit Amana Toyota, Kasaragod but my uncle denied saying that there is an FNG mechanic at Mangaluru who is an AC expert. I agreed, Uncle took the vehicle with him to Mangaluru. Next day, I got a call from him saying that there was a leak in the HVAC pipe located in the bonnet area from where the coolant was leaking. A 'jugaad' by welding (no idea which type of weld) was done by the FNG mechanic that solved the issue.

Coming back to the precious two visits to ASC, I was not satisfied at all. I raised this matter to Toyota Kirloskar Motor over email as why the ASC failed to detect a simple leak in the AC unit even after charging heavily? Next day, got a call from one of the customer care personnel and I briefed them about the same requesting this should not happen with other customers who trust Toyota and their sound technical expertise.

It has been around 3+ years after this issue was fixed and till date, the AC does its job pretty well considering the age of the vehicle. However, during extreme heat prevailing in Kerala, the cooling seems to be a little low which is obvious but I have no regrets though!

@Alphard I advise you to get in touch with an FNG mechanic from your area who is well versed with the AC job. Maybe, they can find where the exact issue lies.

Drive safe!
Sud.

[tez_padhye]

Originally Posted by sasta_rider

A SA came, without even trying to recreate the problem, informed that they will have to refill the coolant and check. I said OK, they filled the coolant and handed over the vehicle, AC cooling had come back to normal. This stayed for a week, followed by the same poor cooling. Since I had done the coolant refill at Mangaluru, decided to take it all the way there for another round of diagnosis. This time, a different SA (previous SA was on leave), informed me that they will have to remove the dashboard, check for any leaks and only then can conclude why the cooling is almost nill. I agreed, kept the vehicle for a day and left to my relatives place nearby. Next day, when I went to pick the vehicle, the bill was hefty, which as expected. This included the labour to remove and fix the dashboard along with refilling of coolant.


Sud.

Thanks for sharing and good to know it was a simple fix that could be carried out by an FNG. Company SA's dont have the knowledge as the mechanics do but the mechanics have to follow what an SA issues in the jobcard. Usually the SA's main goal is to ramp up labour and other part charges while they know the inner workings of the parts and machinery.
Also its refrigerant that is filled in the AC system. Coolant is what goes in a car's radiator system.

[vigsom]

Thank You, @Alphard, for reporting this issue. I've all along associated the older Toyotas with fuss free ownership (related to fool proof engineering) but this is news. Sharing my thoughts.

Originally Posted by Alphard

When the AC starts cooling, the AC will keep cooling regardless of how many KMs or Hours the vehicle is driven.However if the vehicle is stopped and then restarted, the problem with AC is indicated by the AC control panel going dead and blinking of the AC defogger light (i.e. the small amber coloured LED on the defogger button on the AC control panel) for about 20 -25 seconds. Once the AC defogger lamp stops blinking, the AC control panel starts - however the AC may or may not cool the cabin.Moreover, this problem seems to affect only the front AC air vents on the dashboard - the rear AC vents keep cooling the cabin

The fact that the rear AC vents are cooling means the compressor is on and the cooling circuit is fine. The rear AC is only a cooler. However, the front has all the main controls, and that is where the issue lies. The fact that the AC panel goes dead and defogger is blinking clearly points to an electrical issue, either due to power supply or due to a signal input error. The issue could be with one or more of the following:

1. Relays/ fuses - other than the ones related to the compressor, because the compressor runs anyways cooling the rear side
2. Could be the ECU main relay too
3. Any of the temperature sensors wiring connections. I doubt if a Denso sensor would have gone bad

I'm sure the Toyota technicians would have looked at some of these but still calling this out.

Just for your reference, the following video shows the Innova compressor cutting on and off

https://www.youtube.com/watch?v=C6O4utZkDrg

I'm not sure if there was some other issue in May-2023 that was "attacked" post which you started experiencing this issue. Did you face some water ingress into the engine bay fuse box, or something similar on the inside, or some other electrical issue that was addressed or an accessory that was installed? If no, what I'd suggest is to change the relays and see. If it still doesnt solve the issue, decouple the wiring coupler to the hot air flap and the fresh air intake. Let the AC run only in cool mode and see.

[Alphard]

Thank you to all for your valuable responses.

I did check with the Toyota ASC about any error codes that may have been logged in the system however I was told that this particular area does not have any diagnostic codes.This can as surprise to me but then my vehicle is 13 years old.

I think there would be electric actuators to control the valves that regulate the air flow however I don't know if the Toyota ASC took the time & efforts to examine them despite having the vehicle with them for adequate time.

From my understanding, the problematic behaviour is and was same with the old as well as the newly replaced control panel.

Based on your advise, I think the best thing for me would be to consult a FNG mechanic who is well versed with the AC job. Any recommendations in and around Pune would be of great help.

[Alphard]

Hello Vigsom Sir,

Thank you again for your detailed response (as a matter of fact, I had posted the same issue in one of your old threads to get your opinion on this issue).

During my visits to the Toyota ASC, I had urged them several times to check all the relays and the electrical wiring as part of the troubleshooting - based on the online search for similar problem symptoms, one thing that repeated came up was a "faulty magnetic clutch relay" but I couldn't locate the same in my vehicle.

There has been no incident of water ingress into the engine bay or inside the cabin nor was there any electrical issue that was addressed recently. However I did replace the old factory fitted head unit with an android head unit in March this year. The head unit is a simple one and its specifications don't indicate that it would draw excessive power. (this problem used to occur even prior to the head unit replacement also but at much lesser frequency). This aspect was verified by Toyota ASC as well - I gave them the original head unit too so as to help them troubleshoot the issue.

The intermittent & unpredictable nature of this issue is what complicates the matter further. On my part, I am driving my car more often now so that if the problem manifests itself again, I am better prepared to do basic debugging myself.

Best Regards.