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Chevy S10 - GMC S15 and Sonoma Climate Control



  • danpstewdanpstew Posts: 2
    yes, the large line is cool the small line is warm.
  • gonogogonogo Posts: 879
    The large line at the compressor should be cold not cool, I would think you are low on 134a. It should be checked by a pro, the right way to fill a 134a system is recover and then add the factory amount back. I would say a leak check should be done also.
  • sn4ck0sn4ck0 Posts: 8
    95 S-10, I turn the heater on and the P brake light comes on, and the speedometer goes to Zero, Fuses are ok, every once in a very rare time, I would turn it on, and every thing works fine, but as I'd turn it back off, it'd maybe come back on once (some times it won't), then it won't work properly after that for ages.

    I had read somewhere that it may be a Ground near the Dash Cluster, but I've no Idea where the Dash cluster is at, I've the repair manual as I've had to do many repairs to it, and in the Electrical Diagrams area, they list quite many, many grounds, many more than what I wish to check, I've check and cleaned the grounds in the engine compartment, all are swell.

    Any Ideas?

    Thanks in Advance.
  • gonogogonogo Posts: 879
    Your gauges are your dash cluster.Look under the dash for grounds.
  • sn4ck0sn4ck0 Posts: 8
    I have the entire Dash apart, and I'm not able to find any "actual" Grounds, anyone have an Idea to where the Grounds inside are located?
  • gonogogonogo Posts: 879
    The plug with all the wires, one or more is ground. Now you need to find out where they are grounded, close by I would say.
  • sn4ck0sn4ck0 Posts: 8
    There are about 10 Different Plugs, 4 or five of them, are rather "large".
  • I just noticed that my blower motor only seems to work on 3 and 4 now. I was just wondering if it is a bad blower motor or if the blower motor resistor is bad? Any help would be appreciated.
  • sn4ck0sn4ck0 Posts: 8
    I have heard the Same issues, with the HVAC Switch only working on "high" and the problem being the Blower Motor Resistor.

    If your Blower Motor is working, I think you could rule that out, The BMR, is roughly 17$ of course depending on where you're at.

    As I've just replaced my BMR, trying to resolve another issue, I know it's a simple task to to replace.
  • Ah okay, I was kind of leaning twards the resistor. I looked it up the other day, about 22 bucks at Advance Auto. Thanks for the tip. :)
  • 03gmc03gmc Posts: 2
    I have a 03 sonoma w/ manual climate controls. I have noticed that some one else posted a question about my same issue. With the temp selected to cold and the air flow off I get warm air through my heater, also if I select defog, heater, or blend I still get warm air which is very annoying when it's 60 degrees or warmer outside. Is this normal? All the other GM vehicles I've owned would actually blow COLD air if defog was selected. My A/C works fine. And I can hear my A/C pump engage when selscting defog. I checked my mixing actuator coming off the heater core and it seems to be getting full movement in both directions. Any suggestions?
  • gonogogonogo Posts: 879
    Sounds like the temp actuator is not moving the valve. Is the large line going to the compressor cold on A/C?
  • 03gmc03gmc Posts: 2
    Yeah, The a/c works fine. I was able to observe the temp actuator and it seems to getting full movement in both directions. There are actually reference marks on the duct that coincide with the actuator. They seem to line up also. The only thing I can figure is the temp actuator doesn't quite close the whole way.
  • gonogogonogo Posts: 879
    well with my 99 I have to have dash vent on, or I get heat out the floor vents. Dealer said normal, they all do it.
    The A/C is so cold, I have to modulate with heat or I would freeze, even when 90+ out.
  • I am having trouble with the Head/Feet control. It is a 2001 Chevy S10 with ZR2 Package. When I go to put the air to blow on my feet, so that all the air comes out the bottom, its as if i never moved the switch. It still comes out the top (face). Also when I try to put it on defrost, nothing happens. It only blows out of the 4 vents that point at my face. Any ideas as to what is wrong?
  • gonogogonogo Posts: 879
    Check for a vacuum leak. Under hood drivers side, the hose goes into fender well where vacuum reservoir is located. Trace it out looking for a problem.
  • the_big_althe_big_al Posts: 1,079
    Is the air coming through the dash vents or the floor vents? Dash vents should not be emitting air when the fan switch in the "off" position. When the fan switch is in the "off" position however, the floor vents will always allow air to flow through the vents. You will not notice this if the truck is not moving, but once you get wind passing over the truck while driving, air will flow through the floor vents. This is common on most GM vehicles.
  • TexunTexun Posts: 1
    I have a 98 S10 W\factory air that only cools under acceleration. I thought it was low on refrigerant so I bought a refill kit with a gage. It was at 35psi on the high side so I added just a shot and it's now at 39psi with no change. I do not have a full set of gages so I am unable to check the low side.

    At cold idle the compressor kicks in and cools perfectly. However, once warmed up and at idle or highway cruising speed, the compressor no longer kicks in and the only way to get cold air again is to accelerate. As soon as I accelerate to pass a car the vents start blowing very good and cold air. I checked the low pressure switch on the can, and as far as I can tell it's not receiving voltage when engine is running and warm. As soon as I rev the engine the compressor will kick in again and blow cold air.

    The compressor and dryer were replaced about 5 years ago and I have had no problems of any kind until recently. This has me stumped. I've got a long road trip ahead of me and I live in the south. Any suggestions would be appreciated
  • I have an 03 S10. The vent control has a vacuum leak behind it that can be heard. I took it out and found the rubber piece which directs the vac flow had swelled so that it did not fit the metal backing piece which presses the rubber piece against the vacuum manifold. I replaced it and it worked fine for a while and then it swelled again so the noise is back and it doesn't work. Does anybody know what"s going on here?
  • I am having a similar problem with my 01 sonoma. The heat worked fine this morning but after work it would only work on 2 and 3. Would this more likely be the switch in the truck? My guess is on 4 its bypassing the resistor correct? I used a volt meter and at the plug for the blower i get no voltage when on 1 or 4.
  • the_big_althe_big_al Posts: 1,079
    It seems that my heater is taking awhile to get warm. I have a 2001 4.3 V6 S-10. It used to be that the heater air would start getting warm as soon as the temp gauge moved past the 100 mark on the temp gauge. It only took maybe a mile of driving before it was warm enough to turn on full blast and not be chilled by the air.

    However, just recently the air won't get warm at all until the temp gauge reached 210 (midpoint) and then it would go from cold (not lukewarm, not even cool, but mostly cold - as cold as the outside air), to almost instantly hot. Almost like if you were to turn the cold water off on a faucet at the same time you were turning on the hot water. What is it that controls and regulates the airflow from hot or cold? Is there a valve somewhere that opens and closes? That is my first thought because the heater air is eventually hot. It gets as hot as it should and always has, it just takes until the truck warms all the way up to the midpoint temp which is 210. After that it stays warm, even if I shut the truck off for a couple of hours and come back later. As long as the temp hasn't dropped all the way back down to below 100 the heater stays warm.

    I should also note that I a while back, the switchover from floor to dash to defrost started taking a little longer as well as it seemed that the switch from fresh to re-circ A/C wasn't always happening. Again I have figured a slow moving valve and for the most part those switches always happen and I was able to mostly solve the recirc to fresh air switch by having moving from one to the other repeatedly and it seemed to "correct" the issue to the point that it is certainly usable but not and instant switchover from one mode to the next. It takes several seconds to switch from one mode to the next.
  • gonogogonogo Posts: 879
    The heat is controlled by a electric actuated door. It directs air through the heater core for heat and outside air for cold. Usually when door motor breaks you stuck in one mode. The heater cores have been known the plug, usually it give low or no heat.
    Reverse flush is the way to clear a heater core, from the pump side out the head side.
  • the_big_althe_big_al Posts: 1,079
    but what if I have good heat eventually?? The heater will get hot as soon as the temp reaches the 210 operating range, just not until then. It used to gradually warm up until then and was warm enough to operate as soon as the needle moved past the 100 mark, but not it stays completely cold until the 210 mark.... the system I'm sure needs to be flushed as it's been about 4 years since it was done so maybe that's the issue. Too bad the weather is trying really hard to warm up otherwise I would be more worried.
  • the_big_althe_big_al Posts: 1,079
    Here's a truly odd one. I think I solved the heater issue I was having though. I checked the coolant level and found that it was low. I added more coolant and all seems fine now. It is time for a coolant flush though. All three of my vehicles need it as well as 2 of them need an oil change... Looks like a good half a days work.

    Anyway, I am experiences a quirky turn signal. It is on the driver's side. It only happens when the lights are on and then only intermittently. When it happens it acts like a bulb is burnt out with the fast and short blinking. Only there are not any bulbs out. When it has happened, I have gotten out of my truck to see what is happening. The front seems fine. However, the rear lights are where the quirk is. When the turn signal is on the bright lights up, but near as bright as it should. When it goes of, the reverse light, driver's side license plate light and tail-light illuminate. Then alternates back to a not as bright turn signal.

    It's hard to explain... maybe I'll try taking a video of it when it happens again and posting it. But at this point I am at a loss as to where to even begin.... :confuse:
  • atls10atls10 Posts: 1

    I had this same exact problem and after trying a few things it ended up being the clutch on the A/Ccompressor. Once you replace this you'll be good to go, I haven't had a problem was an immediate fix. Hope this helps.

  • My 2001 Jimmy has the same problem. The AC works great, plenty of heat but can't switch between defrost and floor. The problem was a broken shaft on the air door. This is the one controlled by the air motor directly above the accelerator pedal. It has two vac lines (red and blue) running to it. That's the good news. Bad news is repair requires removal of the dash board then the assy that houses the heater core. No easy task - takes many hours. I will attempt to photo sequence and post as I complete this repair.
  • As of 12-12-09 Rock Auto had them for less than $13.
  • The air control flapper inside the heater box is broken. It's the one controlled by the vac motor with red and blue lines.
  • a man just read this post, the relay is the lil silver box just 2 the rite of ur motor, if that is fine follow the wire to the firewall and check the resistor switch
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