AC Fan Question!!!HELP!!
05-10-2011, 09:10 PM
#1
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AC Fan Question!!!HELP!!
Hey
I got my AC fixed today and it appears that there is a thermal fuse on the back of the fluid tank. It appears that that is what failed before I bought it. The low pressure switch is on the input to the fluid tank. Then on TOP of the tank is the
outgoing hose. The hose fits into a BLOCK that is screwed into the top of the fluid tank. Its that BLOCK that has the hose takes the fluid out of the tank. On that BLOCK there are three plugs. One connects to the hose going out. The second plug is just a plug screwed into the opposite side of the hose fitting. Its the THIRD plug that looked like some kind of thermal plug that was filled with solder. I am guessing this was a LOW TEMP solder. It MELTED and let the gas expel. Hence NO A/C! The mechanic appears to have put a solid plug in that spot now. He filled it with R12 and NO LEAKS!!!.
HOWEVER the Condenser FAN doesnt WORK!!!!!. I am guessing THIS is why that thermal PLUG failed. The temp got too high and the thermal plug melted, because the fan never engaged OR engages.
Now the system works and the FAN doesnt spin. I think that if I keep going on like this I will have the SAME failure I had to begin with.
SO NOW I need to figure out WHY the fan doesnt work. HOW does the fan come on in the first place? We shorted the fan and it works fine.
WHAT things should I look for? What causes the fan to come on in the first place? Is there a way to SHORT the fan to have it come on when the car is turned on so that I dont blow the system up while the summer is here? I feel I need to do that while I trouble shoot the system because HERE its going to be over 90 degree interior temps till probably Mid October from now on.
Thoughts? Help? Suggestions?
I got my AC fixed today and it appears that there is a thermal fuse on the back of the fluid tank. It appears that that is what failed before I bought it. The low pressure switch is on the input to the fluid tank. Then on TOP of the tank is the
outgoing hose. The hose fits into a BLOCK that is screwed into the top of the fluid tank. Its that BLOCK that has the hose takes the fluid out of the tank. On that BLOCK there are three plugs. One connects to the hose going out. The second plug is just a plug screwed into the opposite side of the hose fitting. Its the THIRD plug that looked like some kind of thermal plug that was filled with solder. I am guessing this was a LOW TEMP solder. It MELTED and let the gas expel. Hence NO A/C! The mechanic appears to have put a solid plug in that spot now. He filled it with R12 and NO LEAKS!!!.
HOWEVER the Condenser FAN doesnt WORK!!!!!. I am guessing THIS is why that thermal PLUG failed. The temp got too high and the thermal plug melted, because the fan never engaged OR engages.
Now the system works and the FAN doesnt spin. I think that if I keep going on like this I will have the SAME failure I had to begin with.
SO NOW I need to figure out WHY the fan doesnt work. HOW does the fan come on in the first place? We shorted the fan and it works fine.
WHAT things should I look for? What causes the fan to come on in the first place? Is there a way to SHORT the fan to have it come on when the car is turned on so that I dont blow the system up while the summer is here? I feel I need to do that while I trouble shoot the system because HERE its going to be over 90 degree interior temps till probably Mid October from now on.
Thoughts? Help? Suggestions?
05-11-2011, 12:59 AM
#2
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The early fan is controlled by a switch in the lower left face of the radiator (coolant over-temp) and by a temperature switch on the A/C receiver/dryer (refrigerant temp, which is NOT a good method of control).
My suggestion is to install a heavy-duty relay to drive the fan that is triggered by the power to the A/C compressor clutch. If you use a relay on the fan and another on the clutch, or just one relay for both plus a diode, you can relieve the under-sized little relay in the HVAC head of the clutch load, amking it much less likely to fail.
Install two relays, NO single-pole, or one relay, NO double-pole.
Move the black wire from the compressor clutch to the relay coil trigger.
Pull power from the jump start terminal with a very short 12 gage or 10 gage lead, then an in-line high-quality 30-Amp fuse, then 12 or 10 gage to the supply terminals on the relay/relays.
12 gage or 10 gage leads from the relay/relays to the fan and to the A/C clutch.
Now the fan runs anytime that the A/C compressor runs, and the little HVAC relay lives longer. This set-up doesn't mess with the coolant temp fan control.
My suggestion is to install a heavy-duty relay to drive the fan that is triggered by the power to the A/C compressor clutch. If you use a relay on the fan and another on the clutch, or just one relay for both plus a diode, you can relieve the under-sized little relay in the HVAC head of the clutch load, amking it much less likely to fail.
Install two relays, NO single-pole, or one relay, NO double-pole.
Move the black wire from the compressor clutch to the relay coil trigger.
Pull power from the jump start terminal with a very short 12 gage or 10 gage lead, then an in-line high-quality 30-Amp fuse, then 12 or 10 gage to the supply terminals on the relay/relays.
12 gage or 10 gage leads from the relay/relays to the fan and to the A/C clutch.
Now the fan runs anytime that the A/C compressor runs, and the little HVAC relay lives longer. This set-up doesn't mess with the coolant temp fan control.