Cooling Fan causing engine RPMs to go higher???
09-10-2007, 06:50 PM
#1
Cooling Fan causing engine RPMs to go higher???
I have a ‘99 F150 XLT 4x4 and I just noticed that when I turn on the heat or the AC I hear something at the engine switching ON and OFF every 10seconds causing my RPMs to get higher for few seconds. I know this is normal with the AC but don’t thing it should be doing it with just the fan when blowing hot or cool air without the AC being ON. Is it normal or not? I don’t think it was doing it before but I could be wrong. Thanks a lot
09-10-2007, 07:17 PM
#2
Old Fart With An F-150
Join Date: Jun 2007
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The ac compressor will run if you are using the defroster so if you are on that setting or the floor/defrost setting you would hear it cycling. It is normal. My .02Cdn.
J.R.
J.R.
09-10-2007, 09:21 PM
#4
Resident A-hole
When the compressor comes on the IAC will raise the idle a little to take up for the extra load. It takes a second to come back down once the compressor is off. If its cycling that fast the freon/R134/Tetraflouramethane is low.
09-11-2007, 09:46 PM
#6
Senior Member
Doggone it - had this eloquent post written up, then I searched the forum and when I came back, everything was gone. So, let's try again -
First - PLEASE, if you don't know what you're doing, don't do it. Not meaning to offend, but it's always tough on these boards to determine what level of experience the poster has.
A/C systems operate at high pressures, and the boiling point of R134 is (-26deg)Celsius (or do we use Centigrade?), or (-15deg)Fahrenheit (that would be U.S. for butt-cold). If something should cut loose, very easy to have permanent physical damage to oneself - thereby cancelling any cost savings in doing it yourself.
My personal thoughts are to put a full set of gauges on the system - both high and low side pressures. While low freon is the hands-down favorite to this problem, there may be other things such as a blocked orifice screen.
Most cheapie refill systems that I am familiar with include only a low-side pressure gauge at best.
If you choose to go this route, want to make sure the low-side pressure stays above the low-pressure cut-out point for the compressor, typically around 22-24 psi. Also, if you choose to do this, please wear appropriate eye and hand protection.
I have a tremendous respect for A/C systems - back in my younger days, I took it on myself to put some freon in a system without the benefit of any gauges. During my test drive, just unbelievably proud of myself for fixing the A/C, a hose blew rather violently, shook the car - this was a hose rated for 600psi.
First - PLEASE, if you don't know what you're doing, don't do it. Not meaning to offend, but it's always tough on these boards to determine what level of experience the poster has.
A/C systems operate at high pressures, and the boiling point of R134 is (-26deg)Celsius (or do we use Centigrade?), or (-15deg)Fahrenheit (that would be U.S. for butt-cold). If something should cut loose, very easy to have permanent physical damage to oneself - thereby cancelling any cost savings in doing it yourself.
My personal thoughts are to put a full set of gauges on the system - both high and low side pressures. While low freon is the hands-down favorite to this problem, there may be other things such as a blocked orifice screen.
Most cheapie refill systems that I am familiar with include only a low-side pressure gauge at best.
If you choose to go this route, want to make sure the low-side pressure stays above the low-pressure cut-out point for the compressor, typically around 22-24 psi. Also, if you choose to do this, please wear appropriate eye and hand protection.
I have a tremendous respect for A/C systems - back in my younger days, I took it on myself to put some freon in a system without the benefit of any gauges. During my test drive, just unbelievably proud of myself for fixing the A/C, a hose blew rather violently, shook the car - this was a hose rated for 600psi.
09-11-2007, 09:58 PM
#7
Resident A-hole
Doggone it - had this eloquent post written up, then I searched the forum and when I came back, everything was gone. So, let's try again -
First - PLEASE, if you don't know what you're doing, don't do it. Not meaning to offend, but it's always tough on these boards to determine what level of experience the poster has.
Absolutly Correct
A/C systems operate at high pressures, and the boiling point of R134 is (-26deg)Celsius (or do we use Centigrade?), or (-15deg)Fahrenheit (that would be U.S. for butt-cold). If something should cut loose, very easy to have permanent physical damage to oneself - thereby cancelling any cost savings in doing it yourself.
I agree
My personal thoughts are to put a full set of gauges on the system - both high and low side pressures. While low freon is the hands-down favorite to this problem, there may be other things such as a blocked orifice screen.
This is correct it could be cutting off due to high pressure.
Most cheapie refill systems that I am familiar with include only a low-side pressure gauge at best.
And include a stop leak that will mess your system up.
If you choose to go this route, want to make sure the low-side pressure stays above the low-pressure cut-out point for the compressor, typically around 22-24 psi. Also, if you choose to do this, please wear appropriate eye and hand protection.
R134 Runs about 40 PSI on the low side @ 80-85 degrees.
I have a tremendous respect for A/C systems - back in my younger days, I took it on myself to put some freon in a system without the benefit of any gauges. During my test drive, just unbelievably proud of myself for fixing the A/C, a hose blew rather violently, shook the car - this was a hose rated for 600psi.
First - PLEASE, if you don't know what you're doing, don't do it. Not meaning to offend, but it's always tough on these boards to determine what level of experience the poster has.
Absolutly Correct
A/C systems operate at high pressures, and the boiling point of R134 is (-26deg)Celsius (or do we use Centigrade?), or (-15deg)Fahrenheit (that would be U.S. for butt-cold). If something should cut loose, very easy to have permanent physical damage to oneself - thereby cancelling any cost savings in doing it yourself.
I agree
My personal thoughts are to put a full set of gauges on the system - both high and low side pressures. While low freon is the hands-down favorite to this problem, there may be other things such as a blocked orifice screen.
This is correct it could be cutting off due to high pressure.
Most cheapie refill systems that I am familiar with include only a low-side pressure gauge at best.
And include a stop leak that will mess your system up.
If you choose to go this route, want to make sure the low-side pressure stays above the low-pressure cut-out point for the compressor, typically around 22-24 psi. Also, if you choose to do this, please wear appropriate eye and hand protection.
R134 Runs about 40 PSI on the low side @ 80-85 degrees.
I have a tremendous respect for A/C systems - back in my younger days, I took it on myself to put some freon in a system without the benefit of any gauges. During my test drive, just unbelievably proud of myself for fixing the A/C, a hose blew rather violently, shook the car - this was a hose rated for 600psi.
What ya see in bold.