I'm curious if one design is better than the other, specifically in terms of reliability. My Accord is equipped with the traditional clutch type compressor, while my wife's Jetta has one of those clutches variable displacement units. One thing I have noted especially on very hot days, is that the Jetta takes significant longer to cool down than the Accord. Neither car has any a/c related problems thus far.
Traditional clutch type A/C compressor VS variable
- Thread starter gregk24
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I've had a clutch seize before, which caused too much force for the starter to overcome.
Has nothing to do with AC performance. My Mazda 3 has a regular clutch on the compressor and the AC performance is anemic and has been since brand new.
From reliability point of view, I have no idea which type is more reliable. I would imagine it's a wash.
From reliability point of view, I have no idea which type is more reliable. I would imagine it's a wash.
There's other factors
Fixed orifice tube/auto adjusting office tube vs TXV
Variable scroll compressors vs standard swash plate
Then you can throw in a Decoupling pulley on the alternator/AC compressor
There's many variables
Fixed orifice tube/auto adjusting office tube vs TXV
Variable scroll compressors vs standard swash plate
Then you can throw in a Decoupling pulley on the alternator/AC compressor
There's many variables
The variable compressors are very problematic vs a clutch.
Variable Displacement Compressors have been around for at least 30 years, Though they had a clutch & the Control Valve is mechanical. The Harrison V5 was the first one I ever ran across.
The new variable displacement compressors use a solenoid (PWM) to control the control valve. These come with & without clutches.
It's a little to soon to call electronic controlled V/D compressors unreliable, GM trucks started using them in 2014 albeit with a clutch & seem to be reliable......A lot of them are replaced for a leaking discharge line.
The earlier V5 & V7 Harrison were known to leak at the body O-rings.....Nothing to do with them being variable displacement. The Harrison HT6 fixed displacement compressor had the same affliction.
Some vehicles (Especially Japanese econoboxes) have poor A/C performance in really hot weather, My wifes 2010 Toyota Corolla & my daughters 2009 Honda Civic are prime example of that. Sure...They will eventually cool the cabin down, But takes what seems like forever on a 107 degree day.
Small evaporator cores, Small condenser cores, & small refrigerant charges add up to poor performance.
My 2500 pick-up & Camaro have huge evaporator cores & blow cold air within seconds of start-up, Both use fixed orifice tubes though I don't think that is a huge factor as I've had THX systems that perform very well in the past. The truck is fixed displacement & the Camaro is mechanical variable displacement.
The new variable displacement compressors use a solenoid (PWM) to control the control valve. These come with & without clutches.
It's a little to soon to call electronic controlled V/D compressors unreliable, GM trucks started using them in 2014 albeit with a clutch & seem to be reliable......A lot of them are replaced for a leaking discharge line.
The earlier V5 & V7 Harrison were known to leak at the body O-rings.....Nothing to do with them being variable displacement. The Harrison HT6 fixed displacement compressor had the same affliction.
Some vehicles (Especially Japanese econoboxes) have poor A/C performance in really hot weather, My wifes 2010 Toyota Corolla & my daughters 2009 Honda Civic are prime example of that. Sure...They will eventually cool the cabin down, But takes what seems like forever on a 107 degree day.
Small evaporator cores, Small condenser cores, & small refrigerant charges add up to poor performance.
My 2500 pick-up & Camaro have huge evaporator cores & blow cold air within seconds of start-up, Both use fixed orifice tubes though I don't think that is a huge factor as I've had THX systems that perform very well in the past. The truck is fixed displacement & the Camaro is mechanical variable displacement.
Both my BMWs (2001 530i and 2007 335i) have variable variable displacement compressors and have been fine. I think the 335 might be clutchless. 210,000 miles on one and 193,000 on the other. Thankfully both have decent capacity systems and work well. Not as well as my partner's 2014 Focus, but good enough.
After owning or extensively drivng a handful of cars with either type ('03 Golf, '06 Jetta, '15 Jetta, '09 MB C300) have variable type, ('10 Mazda 3, '14 Mazda 3, '12 Scion tC) with clutch on/clutch off types I will say I strongly prefer the variable type. The Mazda and Toyota examples I have experienced extensively would noticeably warm up and start spewing humidity during the off cycles.
Will say the Germans just generally cool better when trying to cool a roasting cabin, I was never really happy with how long it took my Japanese cars to cool the interior on a hot summer Georgia or Florida day.
Will say the Germans just generally cool better when trying to cool a roasting cabin, I was never really happy with how long it took my Japanese cars to cool the interior on a hot summer Georgia or Florida day.
Originally Posted By: clinebarger
Some vehicles (Especially Japanese econoboxes) have poor A/C performance in really hot weather, My wifes 2010 Toyota Corolla & my daughters 2009 Honda Civic are prime example of that. Sure...They will eventually cool the cabin down, But takes what seems like forever on a 107 degree day.
Small evaporator cores, Small condenser cores, & small refrigerant charges add up to poor performance.
Toyota put huge compressors and heat exchangers into the bigger Lexus series and their bigger cars, my parent's LS430 has no problem pulling down the cabin temp on a hot day. It uses a variable displacement compressor.
The Prius HVAC system using a semi-hermetic electric compressor does a better job than the Corolla/Echo systems but it does take a while for pull down on a hot day.
Some vehicles (Especially Japanese econoboxes) have poor A/C performance in really hot weather, My wifes 2010 Toyota Corolla & my daughters 2009 Honda Civic are prime example of that. Sure...They will eventually cool the cabin down, But takes what seems like forever on a 107 degree day.
Small evaporator cores, Small condenser cores, & small refrigerant charges add up to poor performance.
Toyota put huge compressors and heat exchangers into the bigger Lexus series and their bigger cars, my parent's LS430 has no problem pulling down the cabin temp on a hot day. It uses a variable displacement compressor.
The Prius HVAC system using a semi-hermetic electric compressor does a better job than the Corolla/Echo systems but it does take a while for pull down on a hot day.
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I prefer VDC's. IME, the engine doesn't feel as bogged down with them. At idle, you also don't get the muggy lapses and vibrations of the clutch cycling on/off.
As far as reliability, my 16 yr old Infiniti had the original Calsonic Kansei VDC and blew super cold air until the day I sold it.
As far as reliability, my 16 yr old Infiniti had the original Calsonic Kansei VDC and blew super cold air until the day I sold it.
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Originally Posted By: mclasser
I prefer VDC's. IME, the engine doesn't feel as bogged down with them. At idle, you also don't get the muggy lapses and vibrations of the clutch cycling on/off.
As far as reliability, my 16 yr old Infiniti had the original Calsonic Kansei VDC and blew super cold air until the day I sold it.
VDCs are close to old school POA/STV/EPR systems - where the clutch only cycled if the compressor needed to be shutdown.
GM created the original VDC and licensed the design to Calsonic.
I prefer VDC's. IME, the engine doesn't feel as bogged down with them. At idle, you also don't get the muggy lapses and vibrations of the clutch cycling on/off.
As far as reliability, my 16 yr old Infiniti had the original Calsonic Kansei VDC and blew super cold air until the day I sold it.
VDCs are close to old school POA/STV/EPR systems - where the clutch only cycled if the compressor needed to be shutdown.
GM created the original VDC and licensed the design to Calsonic.
2005 Cobalt I bought new now has 295K, as far as I can tell it has an expansion valve type system that doesn't cycle compressor like the CCOT systems I'm used to on the 80's (maybe earlier) thru at least early 2000's GM systems. Seems strange the compresor never cycles (other than initial off/on), but the system blows ice cold today as good as it did new - never been opened up so I'm a fan.
Originally Posted By: 379KITTY
2005 Cobalt I bought new now has 295K, as far as I can tell it has an expansion valve type system that doesn't cycle compressor like the CCOT systems I'm used to on the 80's (maybe earlier) thru at least early 2000's GM systems. Seems strange the compresor never cycles (other than initial off/on), but the system blows ice cold today as good as it did new - never been opened up so I'm a fan.
'98-'02 F-Bodies, C5 Corvettes & quite a few Cadillac's have a Fixed Orifice Tube/Accumulator system.....But NOT a Low Pressure Cycling Switch.
While the Vette's & Cadillac's had evaporator temp sensors, The F-Bodies didn't & you can freeze the evaporator up in the "wrong" conditions.
2005 Cobalt I bought new now has 295K, as far as I can tell it has an expansion valve type system that doesn't cycle compressor like the CCOT systems I'm used to on the 80's (maybe earlier) thru at least early 2000's GM systems. Seems strange the compresor never cycles (other than initial off/on), but the system blows ice cold today as good as it did new - never been opened up so I'm a fan.
'98-'02 F-Bodies, C5 Corvettes & quite a few Cadillac's have a Fixed Orifice Tube/Accumulator system.....But NOT a Low Pressure Cycling Switch.
While the Vette's & Cadillac's had evaporator temp sensors, The F-Bodies didn't & you can freeze the evaporator up in the "wrong" conditions.
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