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A/C not blowing cool air
09-21-2010, 08:45 PM
#21
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Leaving the purely mechanical clutch/compressor issues aside, anyone with just a bit more than ½ a brain can learn to diagnose and repair refrigeration systems.
It's REAL easy and the only tools needed to completely tear-down and rebuild an automotive AC system are a gauge set and vacuum pump.
As to the knowledge required you can go to your local library, or a FLAPS (Haynes has a great "automotive AC systems" book), or better yet search the web and find out all you need to know in minutes.
As to the diagnosis and charging, here's the whole thing in two tables:
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There is not one bit of magic involved--though the AC shops try to keep everyone convinced there is, so they can continue to charge hundreds and even thousands of $$ for repairs.
It's REAL easy and the only tools needed to completely tear-down and rebuild an automotive AC system are a gauge set and vacuum pump.
As to the knowledge required you can go to your local library, or a FLAPS (Haynes has a great "automotive AC systems" book), or better yet search the web and find out all you need to know in minutes.
As to the diagnosis and charging, here's the whole thing in two tables:
There is not one bit of magic involved--though the AC shops try to keep everyone convinced there is, so they can continue to charge hundreds and even thousands of $$ for repairs.
Last edited by cliffyk; 09-21-2010 at 08:48 PM.
09-22-2010, 11:32 AM
#22
1st Gear Member
Join Date: Jul 2007
Location:
Posts: 99
"^^^WRONG^^^^^ The compressor is on a clutch. If what you are saying was true then the clutch would not engage, therefore compressor does not run. Compressor and clutch are two different things even though they are attached to one another. When there is no power applied to the clutch it just free wheels. And buying a gauge set is worthless if you don't have a clue what the readings mean, and how to properly diagnose problems."
No not WRONG and I have a large clue to AC work and Cliffy is correct there is no secret to AC diagnoses and repair it is one of the easiest things to diagnose on a car.
Now to a better description that one can understand, yes the clutch freewheels when not engage that part you got correct.
When the A/C is turned on the system looks and the low pressure switch and high pressure switch, when the low pressure switch indicates high and the high pressure indicates low the clutch will engage. On a properly working A/C system the low side will go down and the high side will go up because of the pressure differential in the orifice tube (or expansion valve depending on the car) this expansion is what turns the evaporator cold causing the AC to blow cold air (same thing as poking a hole in the refrigerant can and as the Freon expands out of the can, the can gets cold).
Now depending on the outside air the system will cycle using the low pressure switch reading. The high pressure switch is used to cut off the compressor incase of over pressurization.
If the orifice tube is plugged when the compressor engages the high side will go real high and if the high side pressure switch is bad the compressor will continue to run until the belt slips, engine stalls, or a combination of both. I have seen cars in my shop that the engine will not idle when the compressor is turned on b/c of the pressure built up on the high side.
During this time the AC will not blow cold air, it usually blow hot air and I have seen plenty of time the AC start to work as the blockage moves around in the system. Most of the time the blockage is part of the descant in the accumulator (or dryer).
No not WRONG and I have a large clue to AC work and Cliffy is correct there is no secret to AC diagnoses and repair it is one of the easiest things to diagnose on a car.
Now to a better description that one can understand, yes the clutch freewheels when not engage that part you got correct.
When the A/C is turned on the system looks and the low pressure switch and high pressure switch, when the low pressure switch indicates high and the high pressure indicates low the clutch will engage. On a properly working A/C system the low side will go down and the high side will go up because of the pressure differential in the orifice tube (or expansion valve depending on the car) this expansion is what turns the evaporator cold causing the AC to blow cold air (same thing as poking a hole in the refrigerant can and as the Freon expands out of the can, the can gets cold).
Now depending on the outside air the system will cycle using the low pressure switch reading. The high pressure switch is used to cut off the compressor incase of over pressurization.
If the orifice tube is plugged when the compressor engages the high side will go real high and if the high side pressure switch is bad the compressor will continue to run until the belt slips, engine stalls, or a combination of both. I have seen cars in my shop that the engine will not idle when the compressor is turned on b/c of the pressure built up on the high side.
During this time the AC will not blow cold air, it usually blow hot air and I have seen plenty of time the AC start to work as the blockage moves around in the system. Most of the time the blockage is part of the descant in the accumulator (or dryer).
09-22-2010, 05:04 PM
#23
5th Gear Member
Join Date: Feb 2010
Location: Connecticut
Posts: 2,549
^Sorry ^ I misinterpreted what you were trying to say. I do not need the explanation. For 24 years I have done commercial hvac work for a living just not on cars. Just the occasional side gig. Though I have come to realize since I have joined these forums that most people posting with a/c problems do not have a clue how a/c works. You must have a basic working knowledge on anything that you are going to repair. Not saying that, yes someone can learn that wants to take the time to do research and learn how to do it right. I have worked on many things over the years that people thought was simple to fix. In the end after the frustration was over trying to figure out what they did then fix that and diagnose the original problem it was more money for me. It just seems that most people run out and pick up that can of refrigerant assuming it is low and have no clue what they are doing. And oh well whats a little more. More is better. You do a/c repair and other repairs in your shop so I know you can relate.
09-24-2010, 06:55 PM
#24
2nd Gear Member
Thread Starter
Join Date: May 2008
Location: Liberty City, FL
Posts: 311
Latest update - went to start the car, it was barely turning over, started, hard to keep running, smole from under the hood. I shut it off, popped the hood and the belt had snapped. I think the a/c pulley has been what's making the noise and just froze up.
At this point waiting for a tow truck and towing it to the dealer
We'll see how much this will set me back $$. I'll post back when I get an update, hopefully Sat.
PS. 89K miles, so much positive things I've talked of this car and sh.it starts happening to it, just below the 100K mile mark. ArgGhhhhh
At this point waiting for a tow truck and towing it to the dealer
We'll see how much this will set me back $$. I'll post back when I get an update, hopefully Sat.
PS. 89K miles, so much positive things I've talked of this car and sh.it starts happening to it, just below the 100K mile mark. ArgGhhhhh
Last edited by alexplantman; 09-25-2010 at 07:56 AM.
09-25-2010, 08:02 AM
#25
2nd Gear Member
Thread Starter
Join Date: May 2008
Location: Liberty City, FL
Posts: 311
Damage report from dealer
Ok Ford Dealer called ...
They said I need the following parts:
compressor comp 3$56
accumulator $122
belt tensioner (forgot the $)
Freon (can't remember the $)
PARTS TOTAL $653
plus $751 labor
total $1563
They said that when the compressor locked up it busted the belt, and crap from the compressor busted up the accumulator inside or clogged it up, so I need the accumulator..
I can't afford all that, so for now, I told them to just get it running, so I need the following:
comp $356
belt $57
$414 part totals
labor $422
TOTAL $948
Does the above look legit to you guys? Do I really need the accumulator? ... If not, I'll just take it to get some freon in afterwards or fill it up with that can I bought last week..
This is happening at the worst economical point for me ... agggghhhhh
...They said I need the following parts:
compressor comp 3$56
accumulator $122
belt tensioner (forgot the $)
Freon (can't remember the $)
PARTS TOTAL $653
plus $751 labor
total $1563
They said that when the compressor locked up it busted the belt, and crap from the compressor busted up the accumulator inside or clogged it up, so I need the accumulator..
I can't afford all that, so for now, I told them to just get it running, so I need the following:
comp $356
belt $57
$414 part totals
labor $422
TOTAL $948
Does the above look legit to you guys? Do I really need the accumulator?
... If not, I'll just take it to get some freon in afterwards or fill it up with that can I bought last week..This is happening at the worst economical point for me ... agggghhhhh
09-25-2010, 08:17 AM
#26
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
A far less expensive alternative would be to remove the compressor and install an "AC Delete" idle pulley and bracket.
No AC after that, but it's only $30 + shipping...
No AC after that, but it's only $30 + shipping...
09-25-2010, 08:42 AM
#27
2nd Gear Member
Thread Starter
Join Date: May 2008
Location: Liberty City, FL
Posts: 311
A far less expensive alternative would be to remove the compressor and install an "AC Delete" idle pulley and bracket.
No AC after that, but it's only $30 + shipping...
No AC after that, but it's only $30 + shipping...
It's like an extra $300 to install the accumulator, tensioner, and add freon... That was the difference between $1563 and $948
Is that something they'll need to remove the compressor later on to install the accumulator?
09-25-2010, 10:01 AM
#28
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
I would not recommend option A at all, unless you are planning on having the system charged within the next 45-60 days, 90 at the most. It is not good for the system to sit not evacuated, uncharged, and unused for much longer than that.
The accumulator should be replaced any time the system has been opened up, as it contains a desiccant that can become saturated if left open for any period of time--that said, it's not 100% absolutely necessary as it will dry when the system is evacuated prior to charging.
One other thing, the prices they quote are robbery.
You can get all of those parts at a FLAPS for:
$190 for a rebuilt compressor ($240 for a new one)
$60 for the accumulator
$34 for the tensioner
$20 for an OEM quality belt ($43 for a Dayco Poly-Cog)
$15 for PAG oil
$45 for 36oz of R134a refrigerant
----
$364 + sales tax
Also the labor quote of $751 is a crock, it's a 2 hour job to replace the parts, 45minutes to evacuate the system, and 15 minutes to recharge it; let's say 4 hours tops--unless the charge $180 and hour somebody's about to be zoomed.
So, add-in another $50 for a gauge set and $90 for a vacuum pump and the total (including sales tax) is:
$380 for parts
$53 for a gauge set
$97 for a vacuum pump
-----
$530 if you do it yourself¹--I.e. you save $1000, and could easily resell the gauge set and pump for $100+ if you didn't want to keep them (Hell, I'll buy 'em)...
------------------------------------------------
¹ - As has been stated before in this thread auto AC work is not a magic act--I could train my shih-tzu to do it in 1 or 2 days...
The accumulator should be replaced any time the system has been opened up, as it contains a desiccant that can become saturated if left open for any period of time--that said, it's not 100% absolutely necessary as it will dry when the system is evacuated prior to charging.
One other thing, the prices they quote are robbery.
You can get all of those parts at a FLAPS for:
$190 for a rebuilt compressor ($240 for a new one)
$60 for the accumulator
$34 for the tensioner
$20 for an OEM quality belt ($43 for a Dayco Poly-Cog)
$15 for PAG oil
$45 for 36oz of R134a refrigerant
----
$364 + sales tax
Also the labor quote of $751 is a crock, it's a 2 hour job to replace the parts, 45minutes to evacuate the system, and 15 minutes to recharge it; let's say 4 hours tops--unless the charge $180 and hour somebody's about to be zoomed.
So, add-in another $50 for a gauge set and $90 for a vacuum pump and the total (including sales tax) is:
$380 for parts
$53 for a gauge set
$97 for a vacuum pump
-----
$530 if you do it yourself¹--I.e. you save $1000, and could easily resell the gauge set and pump for $100+ if you didn't want to keep them (Hell, I'll buy 'em)...
------------------------------------------------
¹ - As has been stated before in this thread auto AC work is not a magic act--I could train my shih-tzu to do it in 1 or 2 days...
Last edited by cliffyk; 09-25-2010 at 10:07 AM.
09-25-2010, 10:11 AM
#29
2nd Gear Member
Thread Starter
Join Date: May 2008
Location: Liberty City, FL
Posts: 311
Thanks very much for the detailed response.. Yeah, I'll get the accumulator on there within the next 30 days, when I get paid..
Yeah, it's at the stealership, so I knew I was going to get raped, but I had to get it towed last night and didn't have any choice, just a mess ...I just didn't think they were going to rape me that hard, lol...
The Accumulator and freon, I can take it to an a/c shop in the next town over that is good and cheap, I just couldn't tow it there last night...
I have to get AAA or some other towing memebership, it will more than cover these freakin tows...$95 last night for the 20 mile tow..
And with 89K miles I know more stuff will start breaking down due to wear and tear... but still love my mustang, lol...I'm glad I wasn't on a date or something like that, lol..
Yeah, it's at the stealership, so I knew I was going to get raped, but I had to get it towed last night and didn't have any choice, just a mess ...I just didn't think they were going to rape me that hard, lol...
The Accumulator and freon, I can take it to an a/c shop in the next town over that is good and cheap, I just couldn't tow it there last night...
I have to get AAA or some other towing memebership, it will more than cover these freakin tows...$95 last night for the 20 mile tow..
And with 89K miles I know more stuff will start breaking down due to wear and tear... but still love my mustang, lol...I'm glad I wasn't on a date or something like that, lol..
09-27-2010, 08:42 AM
#30
2nd Gear Member
Thread Starter
Join Date: May 2008
Location: Liberty City, FL
Posts: 311
Ok, I've done a search and can't find squat... I got to replace the accumulator and add the freon.. so I am thinking I can do that myself, since I had bought the freon already; but haven't been able to find any info on replacing the accumulator...
Where exactly is the accumulator located? Do I need any special tool to remove and replace? I see they are under $100, so that's good.
Should one of those freon bottles be enough to refill the system? I have to see how many ounces that can is, but it's the larger one, cost about $30. Will it make a difference weather I do the refill or take it somewhere to get done?
Where exactly is the accumulator located? Do I need any special tool to remove and replace? I see they are under $100, so that's good.
Should one of those freon bottles be enough to refill the system? I have to see how many ounces that can is, but it's the larger one, cost about $30. Will it make a difference weather I do the refill or take it somewhere to get done?