Zim

Thanks for your comment. Did hold in the AC button but clutch still did not engage. Do you know if the sensor at the bottom of the radiator have anything to do with the AC? Perhaps they damaged it or the wiring when changing out the radiator. Or is there any other radiator related sensor or wiring that has anything to do with the AC? Thanks Zim

94 SC400 140K The plastic top of the radiator developed a crack. While the crack was developing I never noticed a hi temp on gauge. However, it was 95 deg weather and did notice the AC not as cold as before (thought it was low freon)). Had freon checked and it had about 35 lbs pressure. Before taking it to the shop for radiator replacement I filled it with water for the drive over (by now the outside temp was 78 deg) and I stuck a digital thermometer in the center AC vent in the car and recorded 43 deg. Also, I turned the AC on and off ~ 5 times and the compressor clutch functioned normally - no noises. Next I drove to the shop (10 min away) and the vent temp upon arrival at the shop is still 43 deg. Everything working normally. Picked the car up last nite after a radiator change (outside air temp about 78 deg) and the AC is now inoperative. Clutch will not engage on compressor, therefore no AC. All fuses looked good (expecially close look at #2, 10, 20). All connections at or around radiator looked good, except for the low level sensor at the expansion tank. The black rubber cover will not cover the wires and stay in place. However, it was like this when I bought the car 1 month ago and the AC worked. Is there some connector that the shop or I have overlooked that keeps the clutch from engaging? Or is the radiator temp somehow interconnected to the AC compressor and I have a bad sensor. Is there something the shop disconnected and failed to reconnect. I just can't believe the AC worked fine immediately prior to the radiator change and immediately after the change it does not work. I am afraid the shop will say it is a bad compressor that "coincidentally" failed when they worked on it. Any suggestions?? Thanks Zim EDIT BTW - the AC button on the dash does NOT flash. It stays on steady. Zim

Good point, but can depend on whether or not the compressor actually blew up internally or not. There are two other reasons a compressor may not run even though it has not blown up. 1. If the refrigerant level is too low the compressor won't run. 2. The magnetic clutch attached to the compressor can screech and smoke and fool the owner into thinking the compressor blew up. If just the magnetic clutch fails it can be replaced. I have found 400,000+ miles of troublefree Toyota compressor life is possible if the following (mostly Toyota provided) operational guidelines are followed: 1. Run the compressor at least once a month and preferably once a week throughout the year for at least 30 seconds and preferably at least 5 minutes. 2. When first starting the compressor after it has been not been used for a week or more, turn it on only when the engine is at low idling speed - don't turn it on during engine warm up, acceleration or at freeway speeds. (because lubricating oil drains out of the compressor when not in regular use) 3. Run the compressor manually for interior cooling as needed, but do not keep the AC controls continuously in Auto mode as Auto mode results in almost continuous compressor operation resulting in more rapid wear of the compressor and magnetic clutch. 4. Periodically check the refrigerant sight glass to make sure the system is not under or overfilled with refrigerant and add refrigerant soon if it gets low. 5. Every year or two clean the dust and bugs off the fins of the AC condenser and radiator with compressed air or low pressure water and detergent. ← Regarding step #4 - where is the sight glass on a 94 SC400? Thanks Zim 140k 94 SC400

What was wrong with your radiator and what did you have to do to fix it? Thanks Zim 94 SC400 140k

I have the hose and gauge for the freon - but do not know what the pressure range is for a fully charged system. Do you know the range? Thanks Zim 94 SC400 140k

I have the hose and gauge for the freon - but do not know what the pressure range is for a fully charged system. Do you know the range? Thanks Zim 94 SC400 140k

The '93 on up models use R134a refrigerant. It's possible that your system is slightly low on R134a after 11 years, but if the cooling still seems good then it might need only 1/2 of a can. When the AC controls are set for maximum cooling, the center dash outlet temperatures of factory original R134a systems should be around 35-42 degrees F. If they are higher then it's a sign the system is at least a bit low on R134a. The most accurate way to measure the refrigerant level is to follow the procedure described in the factory repair manual. This involves locating the refrigerant sight glass and checking it for the presense of a stream of bubbles when the AC system is running and set for cooling. Alot of bubbles indicates too little refrigerant. But if the sight glass is mostly free of bubbles the system is either properly charged or overcharged. When properly charged, the sight glass will briefly become foamy for a second or two when the AC system is shut off. If overcharged the sight glass with stay free of bubbles even after the AC system is shut off. ← Have a 94 SC400 with R134. Seems to be low on freon - at 95 deg outside temp the vents are ~88 deg. At 82 deg outside the center vents are 66 deg. The clutch seems to work properly. Two questions - where is the sight glass you mention, and what are the freon pressure range specs? Is it best to go by filling the freon until the center temp is ~35-40 deg or should I use psi specs? I am concerned about overfilling or overpressurizing and damaging something. Thanks Zim

I have similar problem, only it appears the engine revs up when AC turned on. I checked the freon pressure on the Low side and it was ~30 psi. Anyone know what the normal range is? I have heard the range is ~25-45 psi but do not know for sure. Sure do not want to over-pressurize the freon. Does anyone have the specs? Thanks Zim Further notes - at 82 deg air temp outside the temp tonight, the vents inside the car have 63 deg air. However, on 95 deg days the temp at the vents is ~88 deg. The clutch definately engages when AC button is pushed on, and there are no unusual noises or lights. Seems like it would be low on freon and that is why I'd like to get the pressurization specs. Thanks again Zim 94 SC400 140K ←

I have similar problem, only it appears the engine revs up when AC turned on. I checked the freon pressure on the Low side and it was ~30 psi. Anyone know what the normal range is? I have heard the range is ~25-45 psi but do not know for sure. Sure do not want to over-pressurize the freon. Does anyone have the specs? Thanks Zim 94 SC400 140K