Air conditioning service

posts from hell said:
Like I told you in PM. It was on a Freightliner. They require more freon than your normal car.

My point is that in your OP $85 a freon pound is expensive. I get them at the shop for $10.
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Freightliner... oh that is better explanation. If I see you charge the A/C system in the car or truck with 4 pounds of R134a, you will see me in :iough:

We charge the customers for $85 a freon pound, sometime $100. For shop employees (mechanics only) get free freon for their personal vehicles not their friend's vehicles.
PS: I pm with PFH today, seems ok and no problem.
 
diehardbiker said:
Hmmm, I didn't notice til now. I had two diesel vehicles both has AC and I never had a problem with it, but with gasoline version I usually have to deal with issues on AC. Now that engine speed may be the factor. I can't get my truck diesel engine RPM past 4k, usually stays below 2K RPM.
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I've not servicing the A/C systems of the diesel powered vehicles with R134a only. My last A/C service on a 1984 GMC pick up truck w/diesel 6.1 L V8 (I forget the engine size) and R12 freon in the system, was in 1992.

The R134a compressors love low RPM, stays running for long time. I smogged a 2008 or 2009 VW Jetta TDI, noticed the compressor still runs with HVAC control panel (climate control panel) all off. I double check the climate control panel again, all are shut off but the compressor keep runs all the time. I don't know why. New to me.
 
deafsmogtech said:
I've not servicing the A/C systems of the diesel powered vehicles with R134a only. My last A/C service on a 1984 GMC pick up truck w/diesel 6.1 L V8 (I forget the engine size) and R12 freon in the system, was in 1992.

The R134a compressors love low RPM, stays running for long time. I smogged a 2008 or 2009 VW Jetta TDI, noticed the compressor still runs with HVAC control panel (climate control panel) all off. I double check the climate control panel again, all are shut off but the compressor keep runs all the time. I don't know why. New to me.
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:lol: Since you said that A/C compressor prefer low rpms for longer life, what about the ones on the Honda's VTEC motors that tend to rev high?
 
You may be right, our Cherokee AC has been dead for last few years. Im not bothering fixing it because we do not get hot that often up here. Heating is more important up here. Also, if going out family trip or something like that, we usually take our diesel truck along.

The Highlander said:
It's Jeep thing. I see there is a lot AC problem at the dealership. I believe Chrysler is worse than GM for AC system.

Also I always rev to 5k rpm for enter highway ramp all times and no problem with AC system for over 11 years from Subaru. But it's true low rev is better for AC system.
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It has been years ago that I owned VW diesel (last generation before turbo was added) and I can't recall if compressor is running when AC is off. So don't know, of course it was R-12 back then.

deafsmogtech said:
I've not servicing the A/C systems of the diesel powered vehicles with R134a only. My last A/C service on a 1984 GMC pick up truck w/diesel 6.1 L V8 (I forget the engine size) and R12 freon in the system, was in 1992.

The R134a compressors love low RPM, stays running for long time. I smogged a 2008 or 2009 VW Jetta TDI, noticed the compressor still runs with HVAC control panel (climate control panel) all off. I double check the climate control panel again, all are shut off but the compressor keep runs all the time. I don't know why. New to me.
Click to expand...
 
deafsmogtech said:
I've not servicing the A/C systems of the diesel powered vehicles with R134a only. My last A/C service on a 1984 GMC pick up truck w/diesel 6.1 L V8 (I forget the engine size) and R12 freon in the system, was in 1992.

The R134a compressors love low RPM, stays running for long time. I smogged a 2008 or 2009 VW Jetta TDI, noticed the compressor still runs with HVAC control panel (climate control panel) all off. I double check the climate control panel again, all are shut off but the compressor keep runs all the time. I don't know why. New to me.
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How can I check if compressor run or not. (I still suck with HVAC and very rare to use it at lab because we dont get AC problem so much due Midwest) I learned a lot from you since you live from CA which use AC a lot. Check on compressor clutch engaged? It's kind hard to tell if it's spin or not.
 
Im not sure if it applies to you but every AC compressors I have seen in autos, they do engage and disenage the belt drive.

How can I tell? Easy, put AC on and put it low with high fan. Then observe the front of compressor with belt going though. You may or may not see the center pulley does stop and go while outside pulley constantly going. Yours may have that or not. I don't know for sure.

The Highlander said:
How can I check if compressor run or not. (I still suck with HVAC and very rare to use it at lab because we dont get AC problem so much due Midwest) I learned a lot from you since you live from CA which use AC a lot. Check on compressor clutch engaged? It's kind hard to tell if it's spin or not.
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I think my car needs A/C service. It's not blowing cold enough air.
 
sequoias said:
:lol: Since you said that A/C compressor prefer low rpms for longer life, what about the ones on the Honda's VTEC motors that tend to rev high?
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The computer (PCM,ECU or ECU) use the sensors/switches in the A/C system to energize/disenergize the A/C clutch. A/C compressor will stop early when the engine speed reach high revs like WOT or receive voltage signal from output sensors/switches. What sensors/ switches are used to control the compressor. is TPS, High or Low pressure sensors or switches, compressor speed sensor or engine speed sensor and other sensor ( I forget the name of sensor).
 
deafsmogtech said:
The computer (PCM,ECU or ECU) use the sensors/switches in the A/C system to energize/disenergize the A/C clutch. A/C compressor will stop early when the engine speed reach high revs like WOT or receive voltage signal from output sensors/switches. What sensors/ switches are used to control the compressor. is TPS, High or Low pressure sensors or switches, compressor speed sensor or engine speed sensor and other sensor ( I forget the name of sensor).
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I don't think it right to me.
My former 01 F250 2wd with 5.4L we was cruise at high speed that had rpm up 3,500-4,000. AC were blow FREEZE so I must be image it stay ON all times what rpm but Never try above 4K rpm.


My 00 F350 diesel had 214K. When I got I need put about 2 cans of R132A now it blow so freeze. It blow around 50oF in extremely humidity but no humidity it was around 35oF to 40oF
 
The Highlander said:
How can I check if compressor run or not. (I still suck with HVAC and very rare to use it at lab because we dont get AC problem so much due Midwest) I learned a lot from you since you live from CA which use AC a lot. Check on compressor clutch engaged? It's kind hard to tell if it's spin or not.
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Diehardbiker mentioned exact thing but if you work on OBD-II vehicles, start with a scanner tool first. Why? Computer stored the codes of CTS (Coolant Temperature Sensor) and Thermostat sensor (new to me, found in European cars like BMWs) even the MIL is not turn light on or previous mechanic/DIYer cleared the codes. If no codes, then go over the front engine compartment to inspect the fluid levels like coolant, oil etc. If coolant in radiator is low level or empty, this is problem for A/C operation because the computer will shut the A/C system when the engine reach over 225 degree F or more. Find nothing wrong. Then take a close look at the belt(s) for sign of loose and A/C clutch for sign of yellow/rusty color. Why? Loose belt cause the compressor slippage another one is compressor speed sensor (NOT ALL the cars have one) that computer will read the engine and compressor speed for compare to match speed if the compressor cant pick up speed then computer will shut the compressor down cuz the computer think it is loose belt or seized compressor. Smart computer.

If you dont have a scanner tool, you can check the electric cooling fan motors
(radiator/condenser fan motors) to see if fan or both fans runs with A/C control panel is turn on then check the clutch like Diehardbike mentioned.
If the clutch engaged and runs then put your hand on Low side line at the firewall side not to front condenser, and feel to see if it is very cold and sweat that mean A/C operation is ok if no blow or no cold air inside the car you have HVAC problem inside like broken blend door or bad blower motor or clogged cabin air filter or debris clogged in the evaporator core.
For old cars are much easy to diagnose or fix. Pm me if you have any questions
 
Milwaukee said:
I don't think it right to me.
My former 01 F250 2wd with 5.4L we was cruise at high speed that had rpm up 3,500-4,000. AC were blow FREEZE so I must be image it stay ON all times what rpm but Never try above 4K rpm.


My 00 F350 diesel had 214K. When I got I need put about 2 cans of R132A now it blow so freeze. It blow around 50oF in extremely humidity but no humidity it was around 35oF to 40oF
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I believe the A/C compressor run off and on cycling in no matter what the engine speed is high or low revs because the computer use pressure sensor or switch to turn the compressor on or off cycling to maintain the HVAC temp to cooling the motorist/passengers. Trust me.
Why the vehicles have pressure sensors/switches in the A/C systems? because the computer prevents the compressor damage when the A/C compressor pump over 400PSI or burst freon and same way as electric air compressor.
 
deafsmogtech said:
The computer (PCM,ECU or ECU) use the sensors/switches in the A/C system to energize/disenergize the A/C clutch. A/C compressor will stop early when the engine speed reach high revs like WOT or receive voltage signal from output sensors/switches. What sensors/ switches are used to control the compressor. is TPS, High or Low pressure sensors or switches, compressor speed sensor or engine speed sensor and other sensor ( I forget the name of sensor).
Click to expand...

Yeah, that's what i thought so but I am not sure if all of them have one. I never heard of sensor for AC system before. (not temperature sensor)
 
deafsmogtech said:
Diehardbiker mentioned exact thing but if you work on OBD-II vehicles, start with a scanner tool first. Why? Computer stored the codes of CTS (Coolant Temperature Sensor) and Thermostat sensor (new to me, found in European cars like BMWs) even the MIL is not turn light on or previous mechanic/DIYer cleared the codes. If no codes, then go over the front engine compartment to inspect the fluid levels like coolant, oil etc. If coolant in radiator is low level or empty, this is problem for A/C operation because the computer will shut the A/C system when the engine reach over 225 degree F or more. Find nothing wrong. Then take a close look at the belt(s) for sign of loose and A/C clutch for sign of yellow/rusty color. Why? Loose belt cause the compressor slippage another one is compressor speed sensor (NOT ALL the cars have one) that computer will read the engine and compressor speed for compare to match speed if the compressor cant pick up speed then computer will shut the compressor down cuz the computer think it is loose belt or seized compressor. Smart computer.

If you dont have a scanner tool, you can check the electric cooling fan motors
(radiator/condenser fan motors) to see if fan or both fans runs with A/C control panel is turn on then check the clutch like Diehardbike mentioned.
If the clutch engaged and runs then put your hand on Low side line at the firewall side not to front condenser, and feel to see if it is very cold and sweat that mean A/C operation is ok if no blow or no cold air inside the car you have HVAC problem inside like broken blend door or bad blower motor or clogged cabin air filter or debris clogged in the evaporator core.
For old cars are much easy to diagnose or fix. Pm me if you have any questions
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The electric cooling fan motors still run on when A/C off even engine off due engine's radiator. The old school vehicles use clutch fan. No way to tell for me to know. No one teach me how use scantool for HVAC system. Blah. The compressor speed sensor? New to me.

The bad blower motor is easy to check DMM or scope with AMP thru relay or fuse box.
 
The electric cooling fan runs entirely separate from the engine. It uses the vehicle electric power to run it. While AC compressor has direct connect with the engine, where it turns the compressor by pulley rather than the vehicle power. The vehicle electric power is not enough to run the compressor.

The Highlander said:
The electric cooling fan motors still run on when A/C off even engine off due engine's radiator. The old school vehicles use clutch fan. No way to tell for me to know. No one teach me how use scantool for HVAC system. Blah. The compressor speed sensor? New to me.

The bad blower motor is easy to check DMM or scope with AMP thru relay or fuse box.
Click to expand...
 
diehardbiker said:
The electric cooling fan runs entirely separate from the engine. It uses the vehicle electric power to run it. While AC compressor has direct connect with the engine, where it turns the compressor by pulley rather than the vehicle power. The vehicle electric power is not enough to run the compressor.
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Trust me, The electric cooling fan still run on when engine off and AC off, It's happen to me all times on newer cars and some old cars. That's why there is warning label about fan will on anytime. If electric cooling fan runs separate from the engine then WHY cooling fan still ON when AC was off OR engine off?

Some of my friends removed AC system from racing car and other people that I know old man rebuilt the old school 70's camaro with new motor but no AC system at all. They still need electric cooling fan which good idea to keep engine cool down during rush hours or stop at red light.

I believe electric cooling fan design for radiator and condenser to cool down, not just AC system only.
 
Cooling fan has nothing to do with AC, you are right that cooling fan can come on and off even while engine is off. That is because the coolant sensor sense that coolant is too hot so turned it on.
With one exception where I can understand why you are thinking. During hot summer days, the coolant gets hotter when the AC is running so maybe that is why the cooling fan comes on and off more often when using AC. AC does make engine work harder thus gets hotter.

The Highlander said:
Trust me, The electric cooling fan still run on when engine off and AC off, It's happen to me all times on newer cars and some old cars. That's why there is warning label about fan will on anytime. If electric cooling fan runs separate from the engine then WHY cooling fan still ON when AC was off OR engine off?

Some of my friends removed AC system from racing car and they still need electric cooling fan which good idea to keep engine cool down during rush hours or stop at red light.

I believe electric cooling fan design for radiator and condenser to cool down, not just AC system only.
Click to expand...
 
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