aballard5
New Member
- Joined
- March 15, 2010
- Messages
- 5
- Reaction score
- 0
- City, State
- Proctorville, Ohio
- Year, Model & Trim Level
- '03 Sport Trac
Hello all! I have an a/c problem and need some advice. I have a 2003 Sport Trac 4X4 SOHC 4L.
During the winter months, I noticed that my compressor was cycling on and off about every 4 seconds when the defrost was engaged. No squealing or whinning associated with it, just a loud "click" under the hood and the truck seems like it wants to stall each time it "clicks" when I'm at idle.
After reading tons of information on cliamate controls systems, I learned that the compressor engages in defrost and the constant on/off every few seconds was a pretty sure sign that the system was low on refridgerent.
Now that warmer weather arrived, I went to a local Walmart and purchased a can of 134a with an inline guage and discovered that my pressure level was not low. So, the next step was to take it to a friend who works in a general maintenance garage, but is not an "A/C specialist."
He hooked the truck up to some machine by attaching lines to the low and high-side ports and started watching the guages. Everything looked fine, and the compressor was spinning as it should. Then he opened the throttle and the problem manifested itself.
As soon as the engine reved up, the 4 second cycling started all over again. The high-side pressure gage dropped and the low side started building pressure. Every time the compresser engaged, the low-side pressure would drop a little, the the compressor stopped and the low-side pressure started to increase. When he took the guages off the truck, the low side pressure was reading 70 psi. This was with the A/C on Max and the fan turned all the way up.
Puzzled, my friend broke into the fuse box under the hood and flip-flopped the compressor relay with the horn relay (I think they were 56A and 56B). This seemed to fix the problem, and I stood ont he accelerator keeping it at about 1500 RPMs and everything was good. I left the shop and got no more than a 1/4 mile away and it started again. I drove back and showed him the problem, to which he responded that he still thought it was the relay.
So...charge is good per the machine he had the truck hooked to in the garage. Flipping relays seemed to work for a litlle while, but then it when back to its old ways. I have someone at work telling me it could be the fan clutch and I can test it blowing a fan at the radiator while parked and running the A/C. Also, we disconnected the switch on the low-side port and used a wire to jump it, which caused the compressor to cycle on and off every 4 seconds just as if the switch was plugged in. Any ideas as to what the problem is, or things I can check in order to troubleshoot?
Thanks in advance.
During the winter months, I noticed that my compressor was cycling on and off about every 4 seconds when the defrost was engaged. No squealing or whinning associated with it, just a loud "click" under the hood and the truck seems like it wants to stall each time it "clicks" when I'm at idle.
After reading tons of information on cliamate controls systems, I learned that the compressor engages in defrost and the constant on/off every few seconds was a pretty sure sign that the system was low on refridgerent.
Now that warmer weather arrived, I went to a local Walmart and purchased a can of 134a with an inline guage and discovered that my pressure level was not low. So, the next step was to take it to a friend who works in a general maintenance garage, but is not an "A/C specialist."
He hooked the truck up to some machine by attaching lines to the low and high-side ports and started watching the guages. Everything looked fine, and the compressor was spinning as it should. Then he opened the throttle and the problem manifested itself.
As soon as the engine reved up, the 4 second cycling started all over again. The high-side pressure gage dropped and the low side started building pressure. Every time the compresser engaged, the low-side pressure would drop a little, the the compressor stopped and the low-side pressure started to increase. When he took the guages off the truck, the low side pressure was reading 70 psi. This was with the A/C on Max and the fan turned all the way up.
Puzzled, my friend broke into the fuse box under the hood and flip-flopped the compressor relay with the horn relay (I think they were 56A and 56B). This seemed to fix the problem, and I stood ont he accelerator keeping it at about 1500 RPMs and everything was good. I left the shop and got no more than a 1/4 mile away and it started again. I drove back and showed him the problem, to which he responded that he still thought it was the relay.
So...charge is good per the machine he had the truck hooked to in the garage. Flipping relays seemed to work for a litlle while, but then it when back to its old ways. I have someone at work telling me it could be the fan clutch and I can test it blowing a fan at the radiator while parked and running the A/C. Also, we disconnected the switch on the low-side port and used a wire to jump it, which caused the compressor to cycle on and off every 4 seconds just as if the switch was plugged in. Any ideas as to what the problem is, or things I can check in order to troubleshoot?
Thanks in advance.
