[anandpadhye]

Originally Posted by debuda

To the best of my knowledge, XUV (and most other large utility vehicles) have only 1 compressor but 2 evaporators.

Compressor is the belt-driven machine which compresses the gaseous refrigerant and sends it to the Condenser (the huge radiator-like heat exchanger in front of the radiator) at high pressure.

Very nicely explained Sir ji. If there will be 2 compressors, they should show up amongst the things connected to the accessory (outer) belt.
BTW, how is the rear evaporator coil activated/deactivated?

Thank you!

[Seran Manian]

@debuda: Thanks for the wonderful explanation. So the Temperature control mechanism senses the temperature of the ambient inside (may be the sensor is some where closer to front side than the rear) and controls the compressor on / off mechanism and hence both the evaporators are infact controlled as against the assumption that front side AC circuit is controlled and the Rear AC mechanism is not.

[spkingsley]

Originally Posted by fundagenie

OK XUVians, I decided to do a detailed analysis of the AC flow. Had to do a drive to the railway station today at 4.30 am in the cold bangalore weather . Below are what I have noticed. And I also dont think it is a niggle. And there is a twist at the end....

- The flow changes to face-floor mode at around 28-28.5 deg. And at around 30-30.5 it changes to floor mode. So it meant I could get hot air on my face and hands till 30 deg. Not bad.

- Since the flow changes to face-floor mode at 28deg, the throw of the AC vents in 2nd row becomes weak. Which means a fan speed of atleast 4-5 to maintain a pretty good throw in the second row. Post 30deg, there is no flow from the door side vents. However, hot air flows from the vents below the front seats.

- Since I tried out the first and second rows, decided to check out the third row AC situation also, though I dont use it. Kept the temp at 32deg on the DIS. Hot air from the floor vents of the first and second rows. Here is the twist.... The air coming from the AC vents in the 3rd row was cold...around 18-20deg cold . I waited for a min or so to see if there would be any change, but no change. So adjusted the temp in the DIS to 27-28deg which meant slightly warm air in face-floor mode. Went back and checked the 3rd row AC and it was still throwing cold air. Waited for again a min to see if it would change while playing around with the 3rd row fan speed. Still no change. Its cold air coming from these vents. Not sure if the air would get warmer with more time. Else it means any one travelling in the third row in cold climate would just have a freezing time.

Brings something to my mind. The only time I had used the third row seats was when the car was brand new and the passenger was an old lady relative of mine. The 3rd row AC was On and at the end of the 3hr journey, she said it was really really cold in the back. While the rest of us in the first and second rows were OK as the temp was set at sort of normal. At the point of time, we thought it was probably because the person was old. But right now with the above observation it could be that she was getting the AC at 18-19deg through out the trip while the rest of us at what ever comfortable temp that was set.

So does that mean the 3rd row has a separate AC compressor or something with no possibility of temp control?

FundaG

Small correction - third row has a second evaporator and blower not compressor. It can only cool and cannot heat

[spkingsley]

Originally Posted by anandpadhye

Very nicely explained Sir ji. If there will be 2 compressors, they should show up amongst the things connected to the accessory (outer) belt.
BTW, how is the rear evaporator coil activated/deactivated?

Thank you!

There is no "activation/deactivation" of evaporator. It is only turning On/off the blower over the evaporator

[SDP]

Originally Posted by spkingsley

There is no "activation/deactivation" of evaporator. It is only turning On/off the blower over the evaporator

I doubt that. There is a separate blower control (which has a Off position) and there is a separate on/off switch for the rear-AC.

My understanding is that the main-switch controls the evaporator and the off-position on the rotary blower-control operates the blower on/off.

[fundagenie]

A little OT and not exactly related to XUV. Still felt it might be useful

With my beast approaching its first bday, time to renew the insurance is also nearing. Started checking out and negotiations with various insurance companies. One thing was the loss of NCB as I had a claim last year when the front windshield had to be replaced. So simply out of curiosity I was reading through the 3-4 pages of current insurance policy. And it was then I realised something.

My current policy is with Royal Sundaram and zero dep (bumper to bumper). And as per the policy replacement of the windshield can be done once in a year without loss of NCB, provided no other part was included in the claim. That gave me some hope. So i got in touch with a friend who was arranging me the insurance this time around. He checked regarding this and came back saying the report filed by the insurance agency at the time stated windshield replacement and bumper replacement. There was a small bend to the metal rod behind the bumper which required some repair of 1000 bucks. I could have easily paid this from my pocket and just got the windshield replaced under insurance. However, nothing could be done at this point of time since the report was filed. And at the time I totally missed it out. . Else I could have saved 6-7k as NCB.

So anyone having Royal Sundaram zero dep policy, if you do need to replace the front or back windshield by any chance, make sure you dont lose out on the NCB. Not sure if this clause is present in all zero dep policies.

FundaG

[debuda]

Originally Posted by anandpadhye

BTW, how is the rear evaporator coil activated/deactivated?

Originally Posted by spkingsley

There is no "activation/deactivation" of evaporator. It is only turning On/off the blower over the evaporator

Originally Posted by SDP

I doubt that. There is a separate blower control (which has a Off position) and there is a separate on/off switch for the rear-AC.

My understanding is that the main-switch controls the evaporator and the off-position on the rotary blower-control operates the blower on/off.

I can only guess how the rear evaporator is activated / deactivated as I do not have any definitive knowledge of this system in the XUV.

Unlike what Spkingsley has stated, I do not think that activation of the rear evaporator merely involves switching on the rear blower. If that is the case, then refrigerant would be passing through the rear evaporator coils whenever the AC is ON (even with rear blower OFF) and would cause frosting / icing of the coils. This frost build up would not allow any air to pass over the coils when the rear blower is subsequently switched on. It is precisely to obviate such a situation that all car AC compressor electro-magnetic clutches have a protective interlock so that the clutch would engage only when the blower is running.

My best guess is that the rear evaporator has an electrically operated solenoid valve which physically stops the flow of refrigerant through it till the Rear AC is switched ON. This solenoid valve, in all probability, would have an interlock with the rear blower, i.e., the solenoid valve can open only when the blower is running.

[spkingsley]

Originally Posted by debuda

I can only guess how the rear evaporator is activated / deactivated as I do not have any definitive knowledge of this system in the XUV.

Unlike what Spkingsley has stated, I do not think that activation of the rear evaporator merely involves switching on the rear blower. If that is the case, then refrigerant would be passing through the rear evaporator coils whenever the AC is ON (even with rear blower OFF) and would cause frosting / icing of the coils. This frost build up would not allow any air to pass over the coils when the rear blower is subsequently switched on. It is precisely to obviate such a situation that all car AC compressor electro-magnetic clutches have a protective interlock so that the clutch would engage only when the blower is running.

My best guess is that the rear evaporator has an electrically operated solenoid valve which physically stops the flow of refrigerant through it till the Rear AC is switched ON. This solenoid valve, in all probability, would have an interlock with the rear blower, i.e., the solenoid valve can open only when the blower is running.

SDP query on Rear A/C switch - The rear a/c switch just supplies power to the rear blower speed control.

Yes the refrigerant circulates through the rear evaporator always. If you switch on the rear blower you get cold air. Frosting is likely to happen only if humid air passes over the evaporator coil

Yes the blower and compressor clutch are electrically interlocked but this applies only to the front blower.

[.anshuman]

Originally Posted by debuda

To the best of my knowledge, XUV (and most other large utility vehicles) have only 1 compressor but 2 evaporators.

Hi debuda, Thanks for correcting my statement. Please pardon my ignorance and sorry for posting the wrong info. I was not aware of the exact technical difference.

But i guess even with a single compressor some reserve capacity is kept exclusively for the rear evaporator coil, i say this because in none of these vehicles i have ever experienced any drop in cooling performance from front vents when rear A/C is turned on. Infact, in case of XUV, the cooling is much faster if both the Evaporator coils are used(Front and Rear A/C).

[reevester]

Public Service Announcement:

Guys, over the past two months, I have had two separate punctures in my XUV. Once in the rear-right and once in the rear-left tire (quite weird that its always the rear tires!).

Anyways, on both occasions I had decided to change the tire by myself and faced one huge issue. After you have jacked up the car and unbolted the tires, you will find the tire literally jammed onto the wheel hub. The first time I had a puncture, it was at 11PM in Lonavala! I had to resort to calling the Mahindra helpline (which sucks by the way) to help me out!

The second time I (luckily) was better prepared and had kept a chock of wood and a hammer with myself so I could whack the tire without damaging the rims.

My point being, if you go on extended trips, do ensure that you get your tires dismounted/remounted after every few months. Would save you a bucket load of time and frustration should you happen to have a flat!

Drive Safe!

[SDP]

^^^ Its a valid concern. Although I have had no punctures yet, I have seen the exact same scene at the service center a few times - the mechanic hitting the tyre a few times to disengage it from the disc/wheel-hub. Can't imagine why the disc has such a high affinity for the alloy. Do any other M&M vehicles have this tendency?

[Sisu]

Originally Posted by reevester

Public Service Announcement:

Guys, over the past two months, I have had two separate punctures in my XUV. Once in the rear-right and once in the rear-left tire (quite weird that its always the rear tires!).

Anyways, on both occasions I had decided to change the tire by myself and faced one huge issue. After you have jacked up the car and unbolted the tires, you will find the tire literally jammed onto the wheel hub. The first time I had a puncture, it was at 11PM in Lonavala! I had to resort to calling the Mahindra helpline (which sucks by the way) to help me out!

The second time I (luckily) was better prepared and had kept a chock of wood and a hammer with myself so I could whack the tire without damaging the rims.

My point being, if you go on extended trips, do ensure that you get your tires dismounted/remounted after every few months. Would save you a bucket load of time and frustration should you happen to have a flat!

Drive Safe!

This happened to my Skoda Fabia too. The alloy just sticks onto the hub and substantial force is required to get it off. Had called the Skoda helpline guys the first time it happened.

The prevention for this is to spray the hub with WD40 once the tire is removed and then fix the tire on the hub. Did this for all the tires and never faced the same issue again.

Cheerzzz

[reevester]

Originally Posted by Sisu

This happened to my Skoda Fabia too. The alloy just sticks onto the hub and substantial force is required to get it off. Had called the Skoda helpline guys the first time it happened.

The prevention for this is to spray the hub with WD40 once the tire is removed and then fix the tire on the hub. Did this for all the tires and never faced the same issue again.

Cheerzzz

Sprayed with WD40. But the weight of the tire adds to its 'stickiness' ! :(

[narsi_6989]

Originally Posted by reevester

The second time I (luckily) was better prepared and had kept a chock of wood and a hammer with myself so I could whack the tire without damaging the rims.

Originally Posted by SDP

^^^ Its a valid concern. Although I have had no punctures yet, I have seen the exact same scene at the service center a few times - the mechanic hitting the tyre a few times to disengage it from the disc/wheel-hub. Can't imagine why the disc has such a high affinity for the alloy. Do any other M&M vehicles have this tendency?

Originally Posted by Sisu

This happened to my Skoda Fabia too. The alloy just sticks onto the hub and substantial force is required to get it off. Had called the Skoda helpline guys the first time it happened.

The prevention for this is to spray the hub with WD40 once the tire is removed and then fix the tire on the hub. Did this for all the tires and never faced the same issue again.

Cheerzzz

As Sisu mentioned it happened in my Fabia too. And if I am not wrong this happens in most of the cars. The alloys tend to get to stick to the hub. This is because the first puncture normally happens after 10k-15k kms (being tubeless) and the wheels are there since manufacture and when you remove the wheels you can also observe small amount of rust. I observed. I found it hard the first time to remove the wheels. As a remedy measure, I just used emery paper both on hub and wheel to clean the rust, applied some oil and everything is fine since then. I make it a point to use sand paper and oil during every puncture.

[dhanushmenon]

Originally Posted by narsi_6989

The alloys tend to get to stick to the hub. This is because the first puncture normally happens after 10k-15k kms (being tubeless) and the wheels are there since manufacture and when you remove the wheels you can also observe small amount of rust. .

Ideally you should rotate your tires every 5000 kms for even wear of all the four tires. If not 5k, you should atleast do it every 10k Kms.
If that's done, I think, this problem will have a good solution in addition to the application of WD 40, emery paper and oil.
Additionally, this is good for the wear of the tyres too