AC Compressor designed to not cycle on/off

mclasser · Oct 10, 2015

The compressor in my I35 doesn't click on/off like most compressors do. Once on, it stays running. Apparently, it's just the way these Calsonic Kansei compressors are designed. The Denso units, OTH, in my Hondas are very apparent when they cycle.

Anyone know what's so special about Calsonic units that they don't cycle? The car has auto climate control, BTW. I really like the AC's performance. The black interior cools down within minutes, even after the car's been sitting in a hot parking lot for a while.

Mackelroy · Oct 10, 2015

I think in max ac mode the compressor doesn't cycle on most vehicles, but does in normal ac mode.

mk378 · Oct 10, 2015

It's variable displacement. The compressor continues to spin but slows down the pumping rate when full BTU capacity is not required. Earlier units used internal control via the suction port pressure, but many cars now have electronic control via a solenoid on the compressor.

eljefino · Oct 10, 2015

My $9999 saturn had a CCOT compressor. The "beauty" of it is how it can ramp up the cooling power (drag) at idle. The downfall is how being cool comes first, and accellerating after a red light comes second.

Your nissan probably has more pep so it's not as noticeable. I agree that on/off cycling is kinda goofy.

Chris142 · Oct 10, 2015

Originally Posted By: mk378
It's variable displacement. The compressor continues to spin but slows down the pumping rate when full BTU capacity is not required. Earlier units used internal control via the suction port pressure, but many cars now have electronic control via a solenoid on the compressor.

Some newer cars dont have a clutch! The compressor is connected directly to the belt. If the car is running the Compressor is turning. Kinda of a drag if your compressor locks up. Your stuck with no way to disconnect it from the belt. Atleast on more normal setup the compressor clutch will still allow you to drive.

mk378 · Oct 10, 2015

Originally Posted By: Chris142

Some newer cars dont have a clutch! The compressor is connected directly to the belt. If the car is running the Compressor is turning. Kinda of a drag if your compressor locks up. Your stuck with no way to disconnect it from the belt. Atleast on more normal setup the compressor clutch will still allow you to drive.

Those should have a rubber bushing in the pulley which serves to shear away and let the pulley keep turning if the compressor internals seize. Problem there is that it can shear prematurely and shut down a good compressor.

JHZR2 · Oct 10, 2015

Originally Posted By: mk378
It's variable displacement. The compressor continues to spin but slows down the pumping rate when full BTU capacity is not required. Earlier units used internal control via the suction port pressure, but many cars now have electronic control via a solenoid on the compressor.

+1. Sometimes has a swash plate or a controlled bypass valve. Our vw had that valve and it was the only thing that ever went wrong on it. A new $60 valve and we were set.

Our inverter type compressors on our split AC units at home work different but similar. It's all about how to vary duty of the compressor to the cooling load.

rationull · Oct 10, 2015

Originally Posted By: Chris142
Originally Posted By: mk378
It's variable displacement. The compressor continues to spin but slows down the pumping rate when full BTU capacity is not required. Earlier units used internal control via the suction port pressure, but many cars now have electronic control via a solenoid on the compressor.

Some newer cars dont have a clutch! The compressor is connected directly to the belt. If the car is running the Compressor is turning. Kinda of a drag if your compressor locks up. Your stuck with no way to disconnect it from the belt. Atleast on more normal setup the compressor clutch will still allow you to drive.

Wow, I haven't heard of this yet. Auto climate control taken to the extreme I guess. I would hope in a set like this they'd at least have a separate AC belt that you can remove or cut. Some cars these days do still have separate AC belts even with everything else driven by a single serpentine belt, which is nice.

I had a 1983 280zx that had a compressor that didn't cycle. I didn't realize Nissan was still doing this. Seems like a nice design for smoothness of operation.

SwampSurvivor · Oct 10, 2015

Seems like that would be disadvantageous to fuel economy to have it running.

gofastman · Oct 10, 2015

If it's not pumping against any pressure there is very little power required to turn the pulley. One benefit is that you can always have some refrigerant and lubricant circulating to keep all the components and seals from rotting

Merkava_4 · Oct 10, 2015

I looked up your Infinity. You're not supposed to be using 0W-40.

Quote:
2002 INFINITI I35 3.5L 6-cyl Engine Code VQ35DE
LUBRICANTS & FLUIDS:
Engine Oil
Grade 1......SL
Maximum Performance Signature Series 5W-30 Synthetic Motor Oil (ASLQT)
Performance Plus XL 5W-30 Synthetic Motor Oil (XLFQT)
Performance OE 5W-30 Synthetic Motor Oil (OEFQT) Above 0 F......10W-30
All TEMPS......5W-30 [1]

Chris142 · Oct 10, 2015

Originally Posted By: mk378
Originally Posted By: Chris142

Some newer cars dont have a clutch! The compressor is connected directly to the belt. If the car is running the Compressor is turning. Kinda of a drag if your compressor locks up. Your stuck with no way to disconnect it from the belt. Atleast on more normal setup the compressor clutch will still allow you to drive.

Those should have a rubber bushing in the pulley which serves to shear away and let the pulley keep turning if the compressor internals seize. Problem there is that it can shear prematurely and shut down a good compressor.
The Scion Xbox does not. If the Ac compressor locks up your done.

mclasser · Oct 10, 2015

Ah, variable displacement...of course. I looked in the service manual and the specs page said that as well.

@Merkava_4- Yes, 5W30 is recommended but the manual says 40 wts can also be used. M1 0W40 and Nissan VQ35s appear to be a match made in heaven according to UOAs. If you feel so inclined, type in Nissan VQ35 oil issues on Google. What kind of BITOGer would I be if I didn't experiment with different types of oil?

Merkava_4 · Oct 10, 2015

Originally Posted By: mclasser
@Merkava_4- Yes, 5W30 is recommended but the manual says 40 wts can also be used. M1 0W40 and Nissan VQ35s appear to be a match made in heaven according to UOAs. If you feel so inclined, type in Nissan VQ35 oil issues on Google. What kind of BITOGer would I be if I didn't experiment with different types of oil?

What if tig1 knew you were doing this? He'd be seriously upset.

Jetronic · Oct 11, 2015

Originally Posted By: rationull
Originally Posted By: Chris142
Originally Posted By: mk378
It's variable displacement. The compressor continues to spin but slows down the pumping rate when full BTU capacity is not required. Earlier units used internal control via the suction port pressure, but many cars now have electronic control via a solenoid on the compressor.

Some newer cars dont have a clutch! The compressor is connected directly to the belt. If the car is running the Compressor is turning. Kinda of a drag if your compressor locks up. Your stuck with no way to disconnect it from the belt. Atleast on more normal setup the compressor clutch will still allow you to drive.

Wow, I haven't heard of this yet. Auto climate control taken to the extreme I guess. I would hope in a set like this they'd at least have a separate AC belt that you can remove or cut. Some cars these days do still have separate AC belts even with everything else driven by a single serpentine belt, which is nice.

I had a 1983 280zx that had a compressor that didn't cycle. I didn't realize Nissan was still doing this. Seems like a nice design for smoothness of operation.

the pulley is designed to start freewheeling if the compressor locks up. the belt can just stay.

What you need to avoid though is running low on refrigerant, that ends up with freewheeling pulleys. I've seen them with rivets that break away.

Nowadays, they often have a clutch aswell as a variable swash plate.

Chris142 · Oct 13, 2015

Originally Posted By: Jetronic
Originally Posted By: rationull
Originally Posted By: Chris142
Originally Posted By: mk378
It's variable displacement. The compressor continues to spin but slows down the pumping rate when full BTU capacity is not required. Earlier units used internal control via the suction port pressure, but many cars now have electronic control via a solenoid on the compressor.

Some newer cars dont have a clutch! The compressor is connected directly to the belt. If the car is running the Compressor is turning. Kinda of a drag if your compressor locks up. Your stuck with no way to disconnect it from the belt. Atleast on more normal setup the compressor clutch will still allow you to drive.

Wow, I haven't heard of this yet. Auto climate control taken to the extreme I guess. I would hope in a set like this they'd at least have a separate AC belt that you can remove or cut. Some cars these days do still have separate AC belts even with everything else driven by a single serpentine belt, which is nice.

I had a 1983 280zx that had a compressor that didn't cycle. I didn't realize Nissan was still doing this. Seems like a nice design for smoothness of operation.

the pulley is designed to start freewheeling if the compressor locks up. the belt can just stay.

What you need to avoid though is running low on refrigerant, that ends up with freewheeling pulleys. I've seen them with rivets that break away.

Nowadays, they often have a clutch aswell as a variable swash plate.
Ive seen them not shear.car got towed in because the compressor stopped the engine!

SHOZ · Oct 14, 2015

Here's a video showing how the variable displacement compressors work. Hyundai has been using them for the last three years.

Clutchless Variable Displacement Compressor

AC Compressor designed to not cycle on/off

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