the fan harness i have wires the ...A/C compressor...into the system. (turning the A/C on also turns the fan on). my question is...if the fan comes on with the A/C then why not run it all the time? my thinking was that after 45-50 MPH you don't need the fan. if this is true, then why would you wire the compressor to the fan? it would be on at 80 MPH. ......
I vote disregard A/C on = Fan on and just run a thermostat to your fan. Found at your favorite candy store: http://store.summitracing.com/egnse...n+switch&x=0&y=0&N=+115&searchinresults=false
Normally, the a/c fan is wired together with the a/c compressor's clutch, but if you don't like that alternative, you can always use a thermal switch, and let the fan work only when a specific temperature triggers the temp switch. Even when you use the a/c clutch's signal to operate the fan, I'll recomend you to instal a relay, to handle the fan's amperage load.
Usaually, the hanesses connect to both a thermal switch and the compressor. When you turn on your a/c, there has to be airflow across the condenser for it to blow cold, and when your stoped or at low speeds, thats what the fan is for. At high speed, having the fan on dosen't have much of an effect, but it won't hurt anything. It's needed because even though your a/c is on, it dosen't mean you radiator will be at a high enough temp to kick on the fan. I prefer to run the fan constantly when the a/c is on, like all cars with factory electric fans do.
i don't know to what effect the ...fan on...at 70 MPH will have on the cooling of the rad. looks to me like at some point the air coming in will be faster than the fan ...what effect will that have on the air going through a slower fan? ... will the fan blades act as a solid wall and not let anymore air in ? or 2...will the blades start...turning faster because the air is ...faster? i am leaning to the ...fan on all the time.(thermo. and A/C controlled). ________ ________ posi. trac.
I agree.... I've thrown a serpentine belt on my truck before becasue of the A/C on and the fan off. I run a toggle switch for the fan, and forgot to turn it on and it built up pressure in the A/C line and threw a belt. Luckily didnt lock compressor up. I go w/ the A/C on and fan on vote
i wired everything per instructions today. first thing i noticed was the temp. went to 200 degrees . i shut it off and called around...the temp. probe is set for 210 degrees. this ain't going to happen with my new motor...i pulled the wires off the probe and jumped them together.( fan on with switch) fired it up, went down the road and back (about 15 miles) and let it idle for a few mins. when i got back. ...185 was as hot as it got ...fan on all the time...my vote now to ...charge the A/C ...and see what it does... ... ...
Yea that can happen without airflow in the condenser. W/ R-134a the highside pressures can get up over 300 psi and its really taxing on the compressor, and the higher the temp, the higher the pressure. Thats why you should have a high pressure cut off switch installed in line, but even they don't always help.
It has the factory high/low pressure switches. It was just a fluke as I started the truck and was about to leave but got a phone call. The hood was nosed up against the garage door and absolutely no air was flowing. Only took a few minutes also. It scared me also, as I had just replaced the compressor, flushed the system, replaced the drier, and recharged everything. That is why I recommend a switch that kicks a fan on w/ the A/C I'd also recommend even a small fan installed on just the condensor that comes on w/ just the A/C that way you know everything is ok. and then a bigger one for the Radiator
