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Honda CRV TXV system has be stumped

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  • #16
    Originally posted by vtpsd View Post
    No difference in performance, other than my static pressures now indicate I am slightly overcharged.

    Pressure can not indicate level of charge.
    I am on the road, and don't have the best equipment to view your videos. I was hoping to see the high side bouncing around, indicating a reed valve problem, but I didn't see that.
    The sluggish response of the high side may be more due to where the connection is made (after the condenser) then anything else.
    The low high side reading coupled with the low side dipping quite low, would normally indicate a low charge problem, but you have said it is accurately charged. Like Cusser, I wonder if the charge amount info is correct?
    I don't think the compressor is worn, I understand that you want to take the chance on a replacement, That is fine, but I doubt it is the cause of your problem.
    I agree with your assessment on what and when the system will cycle.
    If a Tx valve is open more than it should be, all that will happen is more refrigerant than can be boiled off in the evaporator will enter the evaporator, the liquid will continue to boil in the suction hose and you will see frosting all the way to the compressor, in the worse case liquid can enter the compressor and damage it with a hyd lock. You will not see low high side and vacuum on the low side.
    Condenser size has very little effect on correct charge, the volume in a condenser is not great and "bigger" condensers are all about surface area not volume. I over sized my condenser and found no change was needed for the charge amount.
    I trust you checked the compressor outlet for excessive heat?


    • #17
      The compressor outlet has only been warm, not hot. I would say around 90-100F. The outlet of the condenser has been about ambient temp (these temps were when I took the video, ambients were pretty low, about 60F.

      I think I need to start at square 1, which is eliminate the small leaks. I do think my compressor has a tiny leak around the shaft, but will only know when I can get it out tomorrow and hold it in my hand.

      I think my txv bulb could be better insulated, but, from how I understand it, I don't know if that could really be the source of my problems.

      I think there is a chance the condenser could be partially plugged, and thus creating the vacuum condition and the lowish high side readings.

      Or maybe all this comes down to a low charge due to the small leaks. As I said earlier, I added a bit more charge and the problems did not improve, but maybe I needed more yet.

      The charge was added by using a postal scale to get the required oz. of r134a. I understand this may not be as accurate as it needs to be.

      I will address the leaks, replace the dryer again, re-insulate the sensing bulb, install the new compressor, and charge with 23 oz. of 134a.

      As Tom said earlier, I have my "parts cannon" out, and shots have been fired. Certainly not the way I like to approach it, but I'm not sure how else to effectively get it working in a weekend's time. Luckily the Denso parts for this car as much cheaper than I expected.


      • #18
        1st: Reasons for low temp/pressure at the high side include > it's low on charge, temps are just too low ambient, it might just be doing circles thru the system not restricted at X valve and a couple not on my mind this second.

        That's why job one is always see if system can work from a well held vacuum to exact proper charge. YOU have to take all care NOT to allow air back in thru whatever you use to charge with. If cans, weight them full but in this case if you really believe the 23oz charge is correct most 134a cans are 12oz. I do suggest making sure first one's empty can weight's tare weight or how you'll do that is measured is then the same for the next. Purge hoses before even attaching them quickly be right there and ready.

        If vehicle is cool/cold and you use cans into vacuum if kept warm hands then pan of warm water not HOT water will get the whole first can into the vacuum. That without engine on at all. Sure, it will still spit some more switching taps should be fractional not much.

        In short the 24oz available with two cans if they are not leaking themselves and really full as stated that's about right. All the weighing would be the empty cans, tools, taps used.

        Yes I use cans now with the adaptor for the idiotic (so far) special flap so none is lost that so far doesn't work. Get the adaptor or others if not those they are marked.

        Off the immediate topic but got a case or two (12 of them) at a place "TRACTOR SUPPLY" just getting rid of them last Fall for about $4 ea. The cans cost that much to make.

        Just the warning I wasted one spun around like some ridiculous joke the idea they self seal obviously didn't work on that one and just hissed out on another! Who thought up that idea should be in some funny farm of no help at all rather wasted product. Just plan if those for issues hope it's not busting the bank on refrigerant now in season I think $12 is the last I saw?
        MetroWest, Boston


        • #19
          A little more info for my Saga. I started taking the car apart today well methodically looking for signs of a refrigerant leak. When I charged the system I put a small bit of dye in the system. I mixed up a little dye with a tiny bit of PAG oil to have an idea of what it might look like. I found it strange that they did not seem to mix well. I looked closer at the bottle, and it is for COOLING SYSTEMS!! It is sold by a company called AC Pro, and in my haste I was mistaken.

          Now I probably put less than 1/8 ounce in the system, but I assume this stuff is water based, so I am sure its not good for the AC system. I did find small evidence of a leak at the outlet of the compressor and one of the crimped hoses.d

          Before I started taking the car apart, I took the suggestion of adding some more r134 for the sake of experiment. As I added more, vent temps dropped and the hissing from the txv went away. I still was getting very little cooling at idle, but good cooling with revs up, and no more negative pressure on the low side.

          I dont feel too smart right now, but I am learning expensive lessons.
          Last edited by vtpsd; 05-31-2019, 08:25 PM.


          • #20
            Oh my,what a mess. ALL moisture must be removed, and all of the system cleaned or flushed. I'm not sure how you would get all the wrong stuff out. Wish I could give you more help, but you are in uncharted territory.


            • #21
              Enemy of A/C is the moisture! Tiny amounts in air contain water such is why a glass of ice water sweats for example. When inside and unseen in A/C that will frost right at X valve then it's not going to behave.

              Lots a posts already have said job #1 is know it's charged to correct amount without the moisture isn't possible in a total well help vacuum. If it can work for even minutes and quit then you can find out why.

              It can be hopeless reading what's in products look for pure stuff the rest is a lie or junk for last ditch attempts or wild effort to get all that out and hope you only had the one problem that you noticed to touch it at all.

              That's where tossing parts just creates new problems you didn't have up to making this so impossible then costly end up write it off as experience in what DOESN'T WORK. That's costly as a learning method as you are finding out this sport isn't a very forgiving sport. Worse is mistakes set you back worse off then if you never touched it too many times.

              The course of learning we don't like to talk about is almost all people that get serious about this made all those mistakes, then the attempt to warn another doesn't seem to be believed. The vast majority of folks think A/C in vehicle think it's just a game to rip you off then see the magic crap out there the motivation is just sell that stuff and who cares to you what horrors it causes.

              You are learning which is costly and time consuming. Best part is hope you can avoid the mistakes the next time one comes along for now see what can be done for this one,
              MetroWest, Boston


              • #22
                As I said earlier, I am starting from square one, after hopefully learning some lessons. I removed the evaporator so I could see if the txv valve is clean, and I noticed there is a slight oil spot coming from the high side solder joint, so I need to replace the evaporator as well as I do not have the know-how to fix that solder joint. There is also a very slight leak at the crimp joint on the compressor high side line, so that will be replaced.

                At this point, the only items remaining that could be contaminated would be the hard lines from the evaporator and the hard lines to the and from the dryer. I will replace the dryer again as well.

                As stated, I should flush the lines that are remaining. Is there a preferred method of doing so? I see you can buy "flush" at the auto parts store, but I am also heard of using laquer thinner. I have the car apart enough that I can get solvent and air into each line effectively. I have an oilless air compressor I can use to try and dry out the solvent as much as possible without putting oil in to the lines.

                I guess the good news is that the lines and oil look clean and clear still, no obvious corrosion or permanent effects from the incorrect dye.
                Last edited by vtpsd; 06-01-2019, 10:29 AM.


                • #23
                  I've used aerosol AC flush on my own systems, purchased from O'Reilly. https://www.oreillyauto.com/detail/b...Flushes+&pos=3


                  • #24
                    I am waiting on the replacement evaporator, but its all ready to try again besides that.

                    I replaced the discharge line that I suspected of leaking, replaced all of the o-rings in the system, replaced the shrader valves. I removed all of the lines and cleaned them with a can of flush from the parts store. The evaporator has been replaced.

                    I added 1/4 oz. of the CORRECT UV dye to the oil in the compressor.

                    My old compressor makes no detectable pressure with a finger over the discharge port while turning by hand. The new compressor will build quite a bit of pressure in just one revolution.

                    The old o-rings in the system were quite brittle, and I think there was a possibility of several leaks throughout the system.

                    When the new evap gets here i will install the TXV and thoroughly insulate the bulb, and then I get to try it again.


                    • #25
                      This is a great "putty" if you will for insulating X valve bulb/hole:
                      Hope this shows?
                      If not Google Moretite Removable caulking: > (it wont show)
                      Why is at least the stuff I have is about flame proof, stays flexible and is removable is also just sticky enough. Meant for sealing windows for a building mostly is just universally useful for a huge assortment of things. Can be painted over if looks matters. Your call if handy with all sorts of things this is a must have,
                      MetroWest, Boston


                      • #26
                        Sorry for two posts for a pic!
                        Try again...….

                        That seems to work for the pic? Stuff is just too handy not to have. Walmart - hardware stores or on line,
                        MetroWest, Boston


                        • #27
                          Well, I think I have everything working. What a learning experience.

                          The old compressor makes no detectable pressure when rotated by hand, so I believe it was weak. I think my original issue was just low charge from several small leaks, plus low performance from the weak compressor at lower RPM.

                          I replaced all the o-rings, the compressor discharge line, condenser, dryer, txv, and evaporator (original had a slow leak at a solder fitting).

                          The car has functioned well thus far, but it has not been very hot yet. The factory system is cycled on and off based on evaporator discharge temp. I felt as though it was cycling off too soon. The discharge temps are about 48F when the compressor kicks off and 54 when it kicks back on. According to the factory service manual, this is correct. The sensor's resistance was correct based on the temp vs. resistance chart in the factory manual.

                          One extra thing I did was spend some time playing with the discharge temperatures. I used a few different resistors wired in parallel with the factory evap sensor to trick the system into making colder air. You cannot go too much colder, or parts of the HVAC system start to sweat. I settled on a 150k ohm resistor in parallel with the factory sensor. I put the new circuit on a switch in the glove box. When you flip the switch, the AC temperature drops down to about to 42-48, which feels much nicer, and appears to to cause any sweating issues.

                          Thank you guys for helping me along the way. I've learned a lot, and hope that I dont have to touch this system for a while.