Friedrich Room Air Conditioner Service & Parts Manual 2014-2015CP15 & CP18 & CP24ERROR CODECH34 High Pressure Error Fault Codes -- As high pressure,comp off over 10 times in 1 hourUPDATE: 9/24/17 -- So, after multiple plot twists with the particular AC that kept giving us this error message and shutting off, we finally got to the bottom of the situation. This model is supposed to be a WINDOW sleeve and WALL sleeve installed capable AC. When it failed, we had it installed in a wall sleeve (proper size), but apparrently it was not vented properly. (Of course, we did not know that for nearly 4 years.) To keep this story clear, I am going to refer to two ACs: "Bob AC" the unit with heat that gave us these error messages and "Stanley AC" the unit without heat that was essentially the same unit that did not give these messages. When we first bought and installed "BOB AC", it failed within 1 month --and out of desperation, we pulled it from its wall sleeve and put it in a different location in our office but this time it went into in a window sleeve. We put "Stanley AC" which was in another location in our office in a window sleeve into "Bob AC's" wall sleeve. Also for clarity, we have 4 of these ACs in our offices, but this "BOB AC" when it failed was brand new and als was the only one that also has HEAT. That said, with respect to BTU and dimensions, all our ACs are the same. So when we moved "Stanley AC" into "Bob's" wall sleeve, it fit and worked and did not give us that same error message and "worked", but it also did not really cool our showroom. Also, what would happen is that the Stanley ACs would just up and die one day. (Yes that means there was more than 1 Stanley that we killed.) So during the hottest week in the summer of 2017, our latest "Stanley AC", the CP24g30 that we put 2 years ago in that same wall sleeve where "BOB AC" used to be - suddenly up and died. Because "BOB AC" had been working for the past two years amazingly well in the window sleeve we moved it to after it failed in the original wall sleeve, I decided to moved "BOB AC" back into the wall sleeve where it originally failed. And, as you might expect -- "BOB AC" failed within 2 hours of installation. Now, we had all sorts of theories as to why the Bob and Stanley ACs failed. One of my team was certain the failure was caused from the AC being in direct sunlight. I didn't agree, but when "BOB AC" was in the window sleeve and working perfectly -- it was even a bit too cold in the zone he was working, the unit was out of direct sunlight. (FYI - I did find info on direct sunlight -- it will impair an AC's efficiency, but it should not cause this failure.) A friend who is an engineer came to examine the situation and he believed that the problem was based on our neighbor building having a large HVAC pointing its exhaust directly at our AC's vent. His theory was that the hot exhaust was overpowering our AC's ability to vent, and he told us to install a sheetmetal barrier over the back of our AC's sleeve to block the other buildings exhaust from going into our AC. Ironically this sheetmetal solution may have been the reason that "Stanley AC" died. Anyhow since Stanley AC never really cooled our showroom even after we installed the barrier my friend recommended, I kept researching what might be the problem. Finally after having a strange conversation with an AC specialist who insisted that I was using a window AC in a wall which is a "no-no", I went back to research the install instructions to verify that I was not crazy. And, there in the install instructions I found the answers. First off, the unit IS both a window and wall AC -- so I was not just forcing a square peg into a round hole. But, for any unit of large capacity that is going to be put through a wall, the key issue for the unit is going to be about ventilation. Why does the capacity matter? It matters because some lower capacity models have been designed to vent ONLy thru the rear of the AC. (BTW those models are very low BTU like 14k and are very expensive like $1000. Our unit is 24k and cost roughly $800.) Anyhow in re-reading the installation instructions (which I never bothered to read because I had the unit installed by "experts") it talked about wall thickness and how much of the AC needed to be exposed for proper venting. The answer BTW is that at least 14" should be venting outside of the wall. As a point of reference, when "BOB AC" was installed in the window sleeve were it worked PERFECTLY -- only 3" of the face of the AC was inside the room and the remaining 23" of sleeve and AC were outside the window...but when both "Bob and Stanley AC" were installed in the Wall sleeve where Bob almost immediately failed and Stanley worked (poorly) until he died, it was very different -- probably 9" inside the showroom, then about 9" of wall, and then about 6" of the back-end of the AC extending out of the wall sleeve outside the building. Essentially and bottom line, we had installed the sleeve incorrectly and the ACs were baking themselves and then dying. In other words, they were NOT venting properly at all. So, after a lot of debate with my trusted handyman, we pulled the AC out and he wrestled with the sleeve and pulled it out of the wall and additional 9 inches. Now 14" of the wall sleeve are exposed to air out of the back of the building. We reinserted the AC -- and now: 1) NO MORE ERROR MESSAGES; 2) NO MORE INSTANT SHUTOFF and even more amazingly - -3) "Bob AC" is working PERFECTLY and the room is now actually COOLED by Bob. (Remember, when we had "Stanley AC" in the same spot, while it did not fail the same way or as quickly -- it also did not cool the room. Had we known we were not venting it correctly, poor Stanley might have lived a long, happy life and kept us cool. )Hope this long story helps others. Good luck.
on Jul 21, 2019