I have a 2000 GMC 1500 that has the 3 knob HVAC , 5 speed blower on left, cold air/hot air one knob center and , air placement knob on right. has AC also. My heater got where it would not blow hot air to the floor and rear seat this winter, very annoying to have only hot air in your face. I had changed the actuator on the bottom of the heater box a couple years ago so I figured it was the one above right of the accelerator pedal, looked to be working while watching it but air never changed, so I ordered a new one. Knowing I may have trouble replacing it as it has a large 2 groove cam on the rear of the actuator. I looked up a few videos online to help, well they were less than satisfying as most people are on YOU Tube, they show more of them selves than a fix. Warm outside today so I decided to change it out, had some trouble getting it out as far as other parts removal first, but the 2 white actuator arms were good shape and turn good,. The new actuator had the position showing as a middle position so I place the control in the middle position too which was to the floor air and it moved to the middle position while watching it. Turned off the power and ignition and removed old actuator., That is where I am at now, I have both of them lying on my bench , they are identical except the original has screws , the Dorman I bought has tabs. The GM one does have a broken main gear thus it does not work right and didn't put the white levers in the correct position when I removed it, I never actually got the new one installed where it was correct, , I moved the levers by hand many times while the actuator was showing the middle up position and still never got it to go all the way left( defrost)or right ( face vents) and if it did it would not come back to center again. So I am asking how do I " time", or "clock" the 2 white levers to the actuator? Did the new actuator "over cam " when it was installed in the wrong position? any tips or tricks would be appreciated. I am not a dunce, I had my own auto repair business thru the 1980s and 1990s, so I know something about mechanic's, just not much about this. Any advise will be taken seriously. Thanks Ron
Thanks for the reply, what I was wondering about was the type of flush needed so as not to harm my system , hoses and seals, like what type of base do you use , a solvent, alcohol , petroleum base that will work for the GMC using R134a Freon type, Ron
I need to flush the A/C system, I am replacing the Compressor , Accumulator , expansion valve, and condenser with new and I want to flush the lines and Evaporator, it uses R134A refrigerant. What is a good type of flush to use and how much do I need? Thanks Ron
I am rural , No parts stores here , I have to online order everything, One Horse town type deal. I made a brass adapter to screw inside the new valve tap I bought and screw onto the 134 can tops, used a O ring to seal it, Just more sh.. to have to deal with, I guess the valve I bought was for a large tank?? the package said for R134A, Who knows. I am sure it was made off shore. Thanks now have to order a can of dye, Its terrible aint it. Ron
Update, I ordered the 3 wire pressure switch ( rural area) and it finally came in last week, installed it ( had a Schrader valve under the connection) plugged it in , fired it up, all is cool again! I just couldn't get the reference wire to give me a signal so it was the cheapest part to get so I started there. OK new question, I have an older Lumina that my granddaughter complains the A/C doesn't work, Yep , the 134A went out of it overnight. I have a new reseal kit for the car and the Accumulator an expansion valve and the 134A ready to go , So I bought a new set of manifold gauges since I really need them, they came without the can tap for the 12OZ cans. I like the top screw on type valve so I ordered a good one, well the threads are toooo big to screw onto the can. the hose tap on the valve fits the yellow hose just right but the can thread on the valve is too large , I don't know what it fits. Can you tell me what the thread size is for the 12oz cans of 134A before I buy another part I don't need? The manifold has the 134 quick couplers with valves that unscrew from the red and blue hoses and the hoses will then screw to the R12 vechiles. The yellow hose it says in the instructions will attach to a 10Lb tank as is and is sold without can valve tap. I need the right size for the automotive 12 oz cans. I want to put some dye in it and use my black light to find the leak then put on the new parts and pull a vacuum and recharge. Ron
I think I will hold out for an original Air resonator I don't think I want to complicate things with a cold Air Kit thank you Doug for that, Jsdirt, Yes I did take the tape off the comp wires looking for the diode to be bad and it is fine, That is when I found the bad air resonator , Clutch works as in my post I can short the wire on the relay that gets the signal form the PCM and the clutch works fine them so I am betting on the 3 wire pressure switch till I find if that will or wont fix it. Ron
Thanks Jsdirt, I am leaning toward the 3 wire switch as bad. My reasoning is simple, something is wrong, nothing has been tampered with or abused, ( I did more abusing the past few days by unwrapping electrical tape to get access to wires and pulling out the PCM so I could flip it around to look for the right wires, and the Relay box to access it, so the switch is a $20 item, I will work my way up the chain I hope. I did find something interesting while looking for a broken wire. I had to pull off the air resonator that lays on top the valve cover and connects to the "throttle body " air inlet via short rubber boot. It had a piece broken off and missing on the underneath side that goes into the rubber boot and was sucking unfiltered air thru that missing piece. I live in a rural area where there are no salvage yards within a couple hundred miles and would have to hunt those down. But GM has discontinued the part and I don't know where to get one at, used it good as long as it in good condition. Any clues where to search? is a 2001 2.2 S10 the black plastic box is about 12"x 6" x6" with a 3 " inlet and 3" outlet. Ron
Ok, had time to mess with the A/C again, yes I had a bad gauge on the 134 Refrigerant hoses I borrowed. The Low Press, gauge worked as suppose to and you use it to allow Freon to flow from can to system or when off it show line pressure from system. I used the 134 hose and put my own gauge on that hose and it registered the same as the low pressure side at 85 psi on the system when off. and the temperature was 95 degrees outside. I traced down the wiring diagram starting from the Climate control head on the dash, the light, blue wire is what sends the signal to the PCM that is mounted on the right fender on the overflow tank. The 3 wire pressure switch shows to have 5 volts on one wire and the other is a ground and one is a signal/reference wire that appears to be a type of ground also. No way to really check that with a meter and a test light. I undid the factory taped wires that run across the valve cover to the compressor to find the diode and check to see if it was broken or not allowing 12 volts to the comp. It was good. Started back on the relay and the wire that comes from the PCM to signal the relay . It was supposed to be a light green/white stripe wire from a location on the PCM to the relay to click the relay on. I never got a signal from the PCM to click on the relay. I pulled the relay box off to check underneath for that wire to see it was broken, it was not and it was Green with white strip. I could not find it on the PCM as there were several green with white striped wires there. Didn't know which one it could have been since it would not send a signal. I feel like either the 3 wire pressure switch is not telling the PMC to send the signal or another sensor is not telling the PCM to make that connection????? I did jump past the #30 and the #85 and caused the compressor to come on and I put in one can of 134 to have some cold air for a bit and while idling I had 45 pounds on the Low side could not say on the high side as I had already swapped back to the bad gauge by then. But by jumping the 2 terminals I could make it work. Ron
Will turn clutch by hand and feel for any resistance. Good Idea on the can of 134 on the gauge line, I don't know if it was a full can or an empty one, it did have a ball valve just above the can so I can isolate it, or I could shut off the can by using the valve attached to the can to be sure it is isolated. I lost the picture of the switch but will snap another one.
Yes it was 100 degree plus out today in the sun when I put the gauges on it. Will look again at the gauges and see what my GMC 1500 says the pressures are, its a 2000 model so should be close to what I need to see since the GMC A/C works fine. I guess I could get a new 3 wire switch and replace that ? Ron
Ok, I have had some time to look at this closer, I only see the one Switch and it has 3 wires, I looked and felt around the Accumulator, its lines and looked at the lines coming and going to the compressor, evaporator and condenser, nothing more of another switch. I did borrow a nice set of gauges that attached to the large High side port and the small low side port on the Accumulator. The Low side gauge is also a valve that allows the 134to go thru it and shut it off too. It also has a ball valve on each hose just above each port connection so 134 loss is very minimal if any. Now the problem is the clutch will not engage ( never do I get a 12 volt reading at its connection) only when I ground the #30 terminal on the relay. So without the clutch engaged I am getting a reading of over 100psi on the LOW pressure side at the accumulator. The gauge is pegged at that reading when I open its valve. Same reading I was getting with the cheap hose gauge. The High side port I am getting a reading of 50 psi. These readings are with no compressor clutch running or engaged, The refrigerant lines starting at the compressor is one large line that goes across the top of the radiator to the Accumulator, the other line is a smaller line that goes across the top of the radiator also and then turns down and goes into the condenser in front of the radiator. the other line coming from the condenser and goes up along the accumulator where the 3 wire switch is and the large refrigerant port is, turns down again and goes into the heater box ( evaporator) where at the top of the heater box a large line comes out at its top and goes to the other side of the accumulator. The A/C has never been serviced or any parts changed, never have I had to add any refrigerant. I honestly think the trouble lies in something electrical? I am probably wrong but think the climate control head is probably bad? I don't know If I had a wiring diagram I could possibly trouble shoot that I have a picture of the 3 wire switch I will try to upload. thank you for any help you may have. Ron
Ok, I will find a set of 134 gauges tomorrow and get the right reading on the pressures. I was calling the condenser the wrong name, Not the one in front of the radiator but the one coming from the "heater box". The "LPCD" is on the line at the bottom of the "heater Box", the larger line is at the top of the Heater box and has the accumulator on it, I do not see any other switch on the lines or accumulator but will stand on my head again tomorrow to see if I missed it. the port I was using trying to fill it with 134 was a port on the accumulator,, Low pressure side, and it would not take any. In the past when I filled other A/Cs the compressor would usually kick on after about most of a can would get into it. I don't think I one hose gauge would fit on the other port, wrong size I think.
Jsdirt, I will get a picture of the switch tomorrow, it is NOT on the accumulator , the Accumulator line comes out at the top of the condenser box and is a big line, this comes out at the bottom of the box and is a small line that turns and comes up next to the accumulator, As far as pressures, I do not have a nice set of 134 gauges, I have a single gauge mounted hose that gives the indications of low, good and too high. I installed a new can of 134 on the hose/gauge and tried to inject it into the system thru the low pressure side port, It would not take any of its contents.
My wife drives around a 2001 S-10 4 cyl. Manual shift that we bought new. Only ever did maintenance and the usual brakes, water pumps etc. The A/C this summer decided not to come on, Meaning the blower works and all the door modes are correct only the clutch on the compressor does not come kick in. First thought was finally low on refrigerant , No it was fine. So I did the fuse and relay look and all was good, so I figure it is a pressure switch or, ground or worse a Climate control panel or the PCM? This model S-10 I think only has one pressure switch that I can see it is near the accumulator but is NOT on the accumulator, it appears to be the High pressure line as it comes from the firewall mounted condenser from its bottom and is a small line. It has 3 wires not the normal 2. The only wire that shows any positive voltage is a wire that appears grey or tan? and the voltage showing on my test light is weak, not a full 12 volts. I also cannot short around any combination of these terminals and cause the clutch to kick in. This while the Climate control is on Max A/C and the dial all they way over into the blue color line. So I check on the relay again by changing it out with working Horn relay, still does not work. and I do not have at anytime a positive voltage on either clutch wire at the compressor, Now while the relay while is installed in the relay box, only slightly raised I can short to ground the #30 terminal and the clutch will engage. #85 and #86 terminals I do have positive voltage on one and also the other when the A/C is turned on. I have looked for bad grounds, and loose connections all over the engine . I only see one pressure switch on the A/C lines and I have looked at every inch of the lines in the grille and everywhere. I feel like it is a bad ground or a bad Climate control head. My CC head does not have a separate switch/button for the A/C only on the right had dial can you turn on the A/C. Can some one help me with a wiring diagram of a clue where to look? No the motor does not speed up when I turn on the A/C. Thank you Ron
I cant ever find the solution that fits my problem on this. I have a 2000 GMC 1500 4wd ,3 door, 5.3 engine 150,000 mile always maintained. Every since I owned it, 9-10 years it has had an air door problem. The problem is only in winter time. I never notice it in summer with the AC on. I like my hot air to blow on my feet and I like a lot of blow. I cannot get enough hot air coming from the vents on the drivers feet or the passengers. I can when I get it up to the defrost or the AC face vents but that is not desirable with hot air. 2 winters ago I even stuffed some red rags in the the outlets under the seat that help the rear seat passengers but still don’t get enough air. Fan works great on all speeds, water pump was changed this summer all pulleys , belts , thermostat all original equipment , heater core changed 4 years ago cabin air filter is changed hoses are hot and the hot air feels good just need it to blow. I am sure it is an air door actuator but which one? The one easiest to get to is the one on the drivers side bottom with the covers removed I can see it working but is it going far enough ? I do not know. Any hints or tricks or I don’t mind changing a actuator if I knew which one . The dash has never been apart , only the heater core and it was doing this before then. I hear no noise when I change the heater AC controls. anyone have a starting place it is fixing to get cold again. Thanks Ron this is the type of heater control I have see picture.
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