Toyota Sienna AC Help

[scmoose]

AC was blowing cold intermittently, then just stopped blowing cold all together. Its not the clutch relay. Ran the onboard AC self-diagnostic function and came back with a code 21 which according to the Haynes manual is Solar Sensor Circuit, what the hell is that. Also a Code 24, which is not in the Haynes manual. I pulled the connection next to where the high pressure port is thinking is a pressure issue. When I pull the plug I can hear the RPM of the motor drop. When I plug it back in I can hear the RPM increase again, but I don’t hear a distinctive click of the compressor clutch engaging. Is it possible that the clutch is engaging, I’m just not hearing it, which then leads me to believe I have either a low or high pressure issue, which then leads me to believe possible leak. I bought a set of manifold gauges but I hate to break them out if I don’t need them. Any help. 2004 Sienna XLT 105000

[Bownut]

Locate your accumilator (SP) (big alum. cannister looking thing) look for the pressure switch on the side (or either on the low pressure side line) unplug it and jump the plug out with a paper clip, if the compressor comes on you are either low on refrigerant or the switch or plug is bad, if you jump it out and it gets cold (like it should), probably bad low pressure switch, not low refrig., and just because the clutch relay is o.k. doesn't mean the clutch is actually engaging (replaced one on the wifes car yesterday). If the fan is not matching speed with the engine at idle (on these hot days) then the high pressure switch will cut the compressor off, pressure will subside and back on again over and over, until you get out on the road and get enough air moving across it.

[Rubberhead*]

I can barely keep up with the technical talk but since it was intermittent before it finally quit, I'm guess it's not your pressure switch but a slow leak that finally got too low.

When it was working did it work at first but then quit after running for a while? If so, I'd almost bet it was low gas. It probably hadn't quit but was freezing up.

[Bownut]

He said "blowing cold intermittently", not getting warmer and then quit, so that's why I said check the pressure switch.

[scmoose]

hooked a set of manifold gauges up the preasure on high side and low side are the same 115.

[btduckcall]

that means the comp clutch is not locking in(comp is not working) you dont even have to start the vehilce, you can turn the vehicle key, then turn your a/c on see if you hear the clutch click. also see if you can spin the a/c clutch. (with key off) have you checked your a/c fuse or relay. not sure what a solar sensor is. your codes should be aleast three digits , on all 96 and newer models, a code 21 on pre 96 is 02 sensor belive 24 is air intake sensor, neither one those codes should have an effect on your a/c

[Rubberhead*]

He said "blowing cold intermittently", not getting warmer and then quit, so that's why I said check the pressure switch.

When an AC unit is losing freon, it will get to the point where it is actually colder because of the low gas, not warmer. I thought you understood that?

[btduckcall]

not to get between you two turf wars, but if it low,it will not freeze up, the low side pressure switch will cut the comp out, somewhere between oh 22 and 25 psi, thus it can not freeze up, if it freezes up most times there is problem in the exp vlv (if the system carries an exp vlv, or on the other side a blocked orfice tube, or thermoatic switch sp ), i see why he would want to jump the low side press switch, it would kick the comp in and you could read your gauges and start more trouble shooting, most of the time. if it the high side you may or may not be able to jump it out, best advise take to a shop that works on a/c 's and are certified. there are alot of things that can be causing the problem.

[Rubberhead*]

not to get between you two turf wars, but if it low,it will not freeze up, the low side pressure switch will cut the comp out, somewhere between oh 22 and 25 psi, thus it can not freeze up, if it freezes up most times there is problem in the exp vlv (if the system carries an exp vlv, or on the other side a blocked orfice tube, or thermoatic switch sp ), i see why he would want to jump the low side press switch, it would kick the comp in and you could read your gauges and start more trouble shooting, most of the time. if it the high side you may or may not be able to jump it out, best advise take to a shop that works on a/c 's and are certified. there are alot of things that can be causing the problem.

Gotcha and I do understand that the low pressure switch turns off the compressor if the low side pressure gets too low. My point was (and still is) that a failing of the low pressure switch would likely be catastrophic. Since the system was intermittent before totally failing, it is still most likely a slow leak.

[btduckcall]

you are right most of the time it does. very seldom does a switch go bad, it does happen, but rarely . at the age of the vehicle i would go with a leaking o-ring , i actually should have asked do you see any signs of oil on the a/c lines, comp, etc., but i would recover the system and hit it with about 400 psi of nitrogen and see if i found a leak

[Bownut]

I was just trying to help a brother out, it is not as simple as it used to be, nowadays it is not simply a mechanical fan clutch, but an electroviscous clutch that is controlled by the PCM at varying percentages of fan clutch engagement, if he were idling and it was not cooling and the compressor did not engage, I would jump the low press. switch and check pressures, if high press. switch was cutting it out and back on I would check to see if fan clutch was engaging and matching close to engine r.p.m. or if compressor stayed on and cooled while moving down the road, make sure condenser was clean. Could be a leaky schrader valve and those plastic caps are not going to stop it. Could be any number of things, couldn't say without looking at it, stealership wanted $880 to replace clutch on the wifes car, did it myself in 1 hour for $125 .

[KRT]

Gotcha and I do understand that the low pressure switch turns off the compressor if the low side pressure gets too low. My point was (and still is) that a failing of the low pressure switch would likely be catastrophic. Since the system was intermittent before totally failing, it is still most likely a slow leak.

Ummmm I've seen low pressure side go into a vacuum....just saying

[Bownut]

(OP) I hope you didn't confuse clutches with me, I am refering to the condenser fan clutch not the a/c compressor clutch, if you are reading 115 on both sides then either the a/c compressor clutch is not engaged, but if it is and you can see it turning then the compressor valves are shot, but not likely since it was cooling good beforehand.

[KRT]

So why do you call them stealerships?

[Rubberhead*]

Ummmm I've seen low pressure side go into a vacuum....just saying

Sure. If there's no gas getting to the low side, the compressor can totally evacuate entire low pressure side.

[KRT]

Sure. If there's no gas getting to the low side, the compressor can totally evacuate entire low pressure side.

I hear you all talking about low pressure switches. If the pressure gets low on the low side then why would the switch not stop the compressor?

[scmoose]

Im throwing in the the towl. Compressor clutch is not engaging. Tried jumbing the high side switch, still wont engage. Can hear the RPM increase when I jump the switch, but the clutch is not engaging. I can rotate the clutch by hand when the van is off, but it doesnt free wheel. rRelay seems to be fine, can here it making when you plug it into the socket. Even tried a like relay same deal, hear it clicking but clutch not engaging. I dont see any voltage going to the compressor through the plug on the frame, obviously or the clutch would engage. Just FYI the codes were not ond a ODB reader, the van has a AC self diagnostic program shows the codes on the instrument cluster. Pulled the negative battery cable, codes cleared, but clutch still does not engage, not to mention the codes did not come back. The bitch is going to the shop. Im done.

[Rubberhead*]

I really need to back out of this because I'm just a shade-tree a/c guy. I don't think all systems have low pressure switches. Even if they do, the switch staying in one position for years, may fail closed so when it's needed it won't open leaving the compressor to run.

[btduckcall]

thank you krt , i belive i stated that, also bownut the reason ''stealership" charges so much is that they have the equipment to pay for, the exp tech's,etc... fan clutch's do go out, and rubber head the exp vlv or drier,accumlator has blockage can send a system into vaccum also, and bow nut if both sides read the same at any giving time it is not the radiator fan clutch. if the fan clutch goes it will make the hi side go up. way up, then the hi press switch wil cut the comp out. a blocked (dirty) cond from bugs, dirt, etc will cause this also.

[KRT]

Dude, you're either low in freon or the compressor is shot......take that advice to the bank. These master techs got you going in circles. Keep it simple. 115 on the low and high is basically atmospheric pressure. Push in the shrader valve on the high side service port, see if freon escapes . If it does then your compressor is gone. If it doesn't then go to Advance and buy some 134 kits and shoot the gas to it.