95 4 runner ac problems/questions?

95 4 X 4 3VZE limited SR5 4Runner. A/C works inconsistently. O.K. on start-up sometimes. When engaged on instrument panel, A/C light is on, system is blowing. When colder or wetter outside seems to work O.K. at all driving speeds. When hot out works part of the time then blows warm air. Fan switch seems off. At lowest position air movement is stronger (more velocity) than second position. At full moves most air, seems O.K. At third position, seems to be same air movement/velocity coming out as low position. Had system charged, no leaks, condenser does not show any oil leaks. Fans in front of radiator engage sometimes (I see them cycle on and off). Other times I see them off when the system is turned on. There are three fan relays under the hood and two A/C relays. Should the fan in front of the radiator come on all the time when the A/C system is engaged? If it is relay related how do you diagnose? Now that its 90 every day, the system doesn't blow cold. When its 70 out, it seems to freeze you out of the cab. Help is appreciated. Any more questions, let me know.

Thanx, confused

Reply to
juniortoy
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JR,

Not an expert on this just been around 20 airconditioners (trucks, combines, tractors, personal auto). Ive had trouble like this, least similiar, there are switches (relay) that tells the system that the pressure on the 'high side' of a the system is too high, and there is a switch that tells the pump to shut off because the low side is too low (that is the reason pumps dont enguage when too low on freon) . that 2nd one you probably can see where the A/C Line goes to the firewall, should have 2 wires going to it. They are like any other electical component produced by the lowest bidder, these can go bad. I haven't done this on a toyota yet, so you better check, but I am betting that the low pressure switch has gone bad, easy fix - autozone napa or dealer part... if it is like my older ford van, the switch screwed on to a valvstem like you see on a tire, so you lose almost no freon. if that switch is going bad sometimes you get a/c sometimes you don't when it gets warmer IMHO.

You would have to tell me, (easy thing to see), check out... is the pump is actually turning, when you're getting nothing but hot air? if so my guess is the above DOES NOT apply, it is prolly something else.

juniortoy enlightened us with:

Reply to
Plowboy

Is the fans in front of the radiator an aftermarket thing? My '93 with

3VZE only has the normal fan.

Reply to
Eddie

Plowboy,

Will check out wiring and look for switch. I'lllook at pump when blowing hot. Belt is turning on compressor all the time. Pump is where? Any thoughts on cooling fan? in front of radiator. Chiltons no help as usual. Thanks for the help.

Juniortoy

Reply to
juniortoy

JRtoy...

You are going to have to be able to notice detals... yes, the belts turn the compressor pully, whenever the engine is turning, but the Pump (My bad trying to save myself some typing, is the A/C COMPRESSOR)....

FYI, the pump is seperated from the circular motion provided by the engine through the belts, via an electrically controlled clutch that is on the pully of the AC pump, that I keep caling the A/c compressor is a pump... it pumps freon inside the hoses. they make nice air compressors too BTW.

Anyway about the Clutch, 99.9% of the time you can see that the percieved center of the pully IS or is NOT turning. plus most make a wee bit of noise when the compressor/pump is turning.

AS far as the fans go, The cooling fans are really 2 jobs for this, 80% to keep the engine cool, because the art of creating AC, produces heat both in that radiator (called a condensor) that is infront of the engine coolant radiator. Plus the engine is given a bit of a load (makes engine warmer). so that fan is for moving more air through the 2 radiators, plus what it does for the A/C system & helps the engine stay in operating zones. Now if the fan isnt on, I can tell you if the engine doesnt overheat 1st, if you arent moving air through the condesor, your A/C's effectiveness drops off pretty fast (hot liquid & hot gas is hard to creat cool air) unless you are at highway speeds then you wont notice it hardly at all, but in 'City Traffic' the AC would seem to quit producing cold air, that is EVEN IF the pump doesnt get shut off just because that circuit knows that fan isnt on.

If the pump isnt turning on when it is hot outside, it might be (I cannot say) because the fan is not coming on, which in turn is NOT sending a 'signal' or closing a circuit, which in effect tells the A/C Pump to shut off.... because in many cases the engine is going to overheat without a fan running. on my car without electric fans, there is NO way that the AC system can tell the fan is spinning ("assumes it is" could seem more like the logic used).

so you have about 3 circuits that have to be completed possibly:

1 low pressure circuit has to be, (probably) in closed state (meaning working/detecting normal) 2 high pressure circuit has to be in (probably) closed state (meaning working/detecting normal) 3 whatever sensor on the A/C pump circuit must be told that the condensor fan IS running OK (meaning working/detecting normal) I can see if any of the above do not, pump wouldn't turn.

now if all of this is happening, you just might have a bad compressor (it is not pumping even though it is spinning)... the colder the air needs to be (to cool off the car, the more pressure the pump has to be able to create) the pressure of the freon in the hoses is regulated by a device that is called an expansion valve, it closes and opens to varying amounts, by temperature.

or like my Motorhome's current state of repair, the Freon gas's "expansion" valve has gone bad. I know this because the high pressure hose reading is low, and the low pressure hose reading is way high...

juniortoy enlightened us with:

Reply to
Plowboy

Plowboy,

Did some of your reccomendations. Ran system on and off. When A/C engaged, pump is activated/turning. When disengaged, pump is off/not turning. Same goes for condensor fan. On when engaged, off when disengaged. Did a test where the sytem is running cold usually in the morning on the way to work. About thirty miles in, system starts to begin to blow warm. Pulled immediately over while everything was still engaged at the same settings. Pump was engaged and fan was running. System was blowing warm. Prior to this blowing cold as ice at same settings. Could the system be low? Didn't see any bubbles in the eyepiece/see through tube on the reciever/dryer at any time. When running hot or cold. Perhaps its this valve your talking about. Thanks for the help to date.

Regards,

Juniortoy

Reply to
juniortoy

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