Air Conditioning causes drag on engine

[Mike Parsons]

Car is a 1999 Corolla GLS with only 40,000 miles recorded and in great condition.  Recently found a/c not working and garage reported no gas in system but could find no leaks.  Now re-gassed a/c works fine initially, but after just a few miles clutch starts to cut in and our frequently and causes noticeable drag on engine.  Am I right to suspect Compressor fault - perhaps bearings - or might it be something more obscure?

[Leo63]

When using air conditioning the the compressor causes a drag on the engine is normal it is more noticeable if the car is ticking over and you switch on the the air conditioning the engine will slow down.

[oldcodger]

3 hours ago, Mike Parsons said:

 but after just a few miles clutch starts to cut in and our frequently and causes noticeable drag on engine.

Depends on what you mean by frequently ?   how often does it cut in  and the how long does it stay on for ?

You can notice a very slight drag on the engine, but typically not that much of a problem, for normal driving.

 

1 hour ago, Leo63 said:

When using air conditioning the the compressor causes a drag on the engine is normal it is more noticeable if the car is ticking over and you switch on the the air conditioning the engine will slow down.

Not what happens on our 2006 model,  at tickover of around 650 rpm when the air con kicks in the ecu raised the revs to around 1200rpm , much less than 1000rpm and you get little cooling effect,  perhaps earlier or later models work  differently ??

[Mike Parsons]

6 hours ago, Leo63 said:

When using air conditioning the the compressor causes a drag on the engine is normal it is more noticeable if the car is ticking over and you switch on the the air conditioning the engine will slow down.

Perhaps I was not specific enough.  Once it starts the a/c clutch cuts in and out every 10/20 seconds and imparts a drag to the car as though the brakes have been gently applied then released - it is very definite.  that is why I wonder if the compressor is effectively seized and applying drag to the engine via the drive belt.  Switch off a/c and the effect disappears.  

[Timmon]

It might be worth getting it checked, as if the Air con has not been working a while, and without gas, the compressor will not like that at all.

Have you had the car a while? If so, and you think it is behaving differently since the air con was regassed, to how it was the last time you had working air con, then your suspicion that there may be a fault is probably correct.

My SAAB compressor failed, admittedly during the 2018 heatwave, so it was under a lot of stress. Prior to that, I kept losing gas, for about 4 years before,  had it re gassed every year, no leaks found. Once the compressor was replaced, it worked faultlessly, no need to regas again.

It failed on the way back from the IOW, and made unpleasant sound and no longer cooled. I got home OK, but got it fixed immediately, as I feared damage to the engine.

Re the operation of the air con, yes, the engine revs will drop for a moment, but usually that is just for a moment. You do feel a small amount of drag, as the compressor takes some energy to operate it. In my Saab, the headlights also dimmed for a moment, and audible clicks as the compressor cut in and out. If you have your air con set very low, the clicks will be more frequent. I am usually happy at around 19 degrees, but if the car is baking when you first set off, the compressor will work hard for 20 mins or so, or permanently hard if you have the temperature set very low. 

[Mike Parsons]

3 hours ago, Timmon said:

It might be worth getting it checked, as if the Air con has not been working a while, and without gas, the compressor will not like that at all.

Have you had the car a while? If so, and you think it is behaving differently since the air con was regassed, to how it was the last time you had working air con, then your suspicion that there may be a fault is probably correct.

My SAAB compressor failed, admittedly during the 2018 heatwave, so it was under a lot of stress. Prior to that, I kept losing gas, for about 4 years before,  had it re gassed every year, no leaks found. Once the compressor was replaced, it worked faultlessly, no need to regas again.

It failed on the way back from the IOW, and made unpleasant sound and no longer cooled. I got home OK, but got it fixed immediately, as I feared damage to the engine.

Re the operation of the air con, yes, the engine revs will drop for a moment, but usually that is just for a moment. You do feel a small amount of drag, as the compressor takes some energy to operate it. In my Saab, the headlights also dimmed for a moment, and audible clicks as the compressor cut in and out. If you have your air con set very low, the clicks will be more frequent. I am usually happy at around 19 degrees, but if the car is baking when you first set off, the compressor will work hard for 20 mins or so, or permanently hard if you have the temperature set very low. 

Thanks for those thoughts.  Fairly obviously something is impeding the compressor from rotating normally and imparting drag through it's belt drive back on the engine.  If it is the compressor itself (perhaps bearings going) I have an expensive repair coming up.  However, I wonder if it is caused by a blockage on the high pressure side, so intend to get that checked first.  Outside my competence and I don't have the equipment, but hope to have an Engineer's report next week.

[Timmon]

Yes, my SAAB cost about £700 to fix. It's a no brainer, it has to be done. If the compressor seizes , I believe it will cause damage to the engine, that was the risk for my SAAB, but not sure about the Corolla set up. 

[VosperD]

I have a 1998 Corolla GS 1.3. The A/C was not working when I bought it.

Had it recharged at my local garage on the MoT and service last September.

With the English climate  you don't get much chance to  test the A/C but used it yesterday and A/C still blows cold air. On switch on the engine revs increase a bit.

I noticed in queueing traffic the revs were increasing and decreasing regularly but all  worked well.

I think this must be a feature of the older systems so  for the moment I'n not too  bothered.

On our later VW Touran (2004) you don't notice from the engine whether the A/C is on or off.

Don

Bristol

[oldcodger]

3 hours ago, VosperD said:

I have a 1998 Corolla GS 1.3.

With the English climate  you don't get much chance to  test the A/C but used it yesterday and A/C still blows cold air. On switch on the engine revs increase a bit.

Don

Bristol

Hi,

You should try and use it for a few minute each week  even in winter as it helps circulate the fluid and oil needed to keep the compressor in good order.

In the winter, switching the A/C on along with the heater on high helps clear any misted up windows.

[hubrad]

On 7/23/2020 at 3:50 PM, oldcodger said:

Hi,

You should try and use it for a few minute each week  even in winter as it helps circulate the fluid and oil needed to keep the compressor in good order.

In the winter, switching the A/C on along with the heater on high helps clear any misted up windows.

^^This. I actually use mine more in winter. It's great! 🙂