# Carrier Error code 34 with more



## yuri (Nov 29, 2008)

VERY rarely do they lose pressure and need adjusting. Yours is dying and unsafe, get a new one.


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## totallylost (Dec 8, 2010)

thanks Yuri, Will do.


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## totallylost (Dec 8, 2010)

Well, the gas valve was replaced a couple days ago, and this morning it started with all the same symptoms/problems again.
Any ideas?
Could there be an inadaquate amount of charge going to the valve to where it won't open the diaphram enough? Or? It's not all the time, so it's tough to figure out.
thanks.


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## kenmac (Feb 26, 2009)

Sounds like a flame sensing problem..make sure you have a good ground & check microamps at the flame sensor


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## yuri (Nov 29, 2008)

Your gas meter and or its pressure regulator may be failing. Had one develop an intermittent problem like that a yr ago and it took me several visits B4 I could catch it in action. Call the gas supplier and NICELY explain the problem to them. They may want to blame the furnace but if you nicely explain that the valve has been changed etc they may come and replace the meter and regulator for free. Yell at them and they will blow you off.


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## totallylost (Dec 8, 2010)

Thankyou. And will check.
I have a gas range and gas fireplace insert, both are running fine. Could the gas main still have an issue, because the range and insert don't use as much?
thanks, it's so hit and miss when it works/not works, it drives you crazy.


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## yuri (Nov 29, 2008)

10-4. They use very little compared to the furnace which will require the regulator to open the internal valve wider and allow more flow.


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## totallylost (Dec 8, 2010)

ok, the people who replaced the gas control valve in the furnace were out to look, since that did not fix the problem. Now their diagnosis is the air inlet duct is too small. It's a 2 inch PVC pipe that runs about 8 feet to outside. He claims that needs to be 3 inches. I pointed out to him the point where it connects to the inducer is 2 inches, so it'll still go down to 2, but a shorter run. He has left off the burner box cover for now to help get oxygen in. Since this is a hit and miss problem(but it was 100% bad today for him to work with), I was going to let the cover be off a couple days before I put a 3 inch pipe. He's thinking the inducer may be getting tired to where it won't pull the air through the 2 inch.
Any thoughts? thanks.


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## yuri (Nov 29, 2008)

If it ran for 11 yrs with 2" pipe it should be okay. I have worked on hundreds of those units and they don't mind 2" pipe unless they are the huge over 120,000 BTU units. They usually require a minimum of 15 feet of pipe anyway. All furnaces that use 3" venting restrict down to 2" at the furnace and that is not a problem. It is actually dangerous to run it with that door off as the gas valve won't modulate properly with it off and may overfire. What is the complete model # and I will lookup the vent size 4U. There is a inlet screen inside the black plastic box where the intake pipe attaches (on some models, not all)and it sometimes gets plugged with leaves/debris. Should not cause an intermittent problem though. Did you call your gas co and talk to them about their meter and regulator?


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## totallylost (Dec 8, 2010)

Hi yuri, the model is 5mxa060-12, serial 14499a00187. It has 10 feet total of straight pipe with 3 90 degree elbows and 2 45 degree turns in the 2 inch inlet air tube. The exhaust has 9 feet straight pipe with 3 90 degree elbows. The 2 pipes end openings are only 4 inches apart from each other. I found the installation manual, score, that the previous owners left looks like the 2 inch pipe is fine, plus the book says to use the same size pipe on both inlet and outlet, so this goes against what the guy was saying. I see the book also says the ends should be at least 12 inches apart from each other.
I put the cover back on while the flame was on, and it definitely seems to choke out the air. I took the pipe off the furnace where the inlet is, and yes there is a metal disk in there, but there was no obstructions. I am going to call the gas company and nicely discuss with them what's going on. Have you ever have a bird or something go into the inlet tube? Since it not a straight shot, I can not look down it, but was thinking of cutting it to see if there is anything in it. The exhaust seems strong. Thanks again for the help. No problems so far with the door off, but am worried about the unstable flame.


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## yuri (Nov 29, 2008)

You could have something floating around inside your intake pipe. We have had garbage bags and a BKing wrapper get sucked into one. Kids also drop golf balls/toys etc in them. That will explain your low gas pressure. With that cover on and a shortage of air it increases the draft/suction in the burner box. That sucks on the hose leading to the gas valve and causes it to modulate closed so you get a proper air to gas mixture. Looks like you may have to replace your intake piping. Try blow it out backwards with a shop vac blower. If it is a floaty floating bag/wrapper like I had then it is impossible to blow out as it won't buildup pressure on it.


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## totallylost (Dec 8, 2010)

Just got off the phone with the gas company. Wow! They send out a tech for free to inspect your furnace. If they find anything , then they charge to fix of course, but great, some more eyes. I'll get out there after work and remove the pipe to inspect for blockage. Thanks for all the help and advice!


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## yuri (Nov 29, 2008)

We have a very good gas co. too who provides some service, now that was easy:yes:


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