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Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
Satisfied Customers: 953
Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
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10 ton Armstrong package heat pump.......8years old........

Customer Question

10 ton Armstrong package heat pump.......8years old........ spiking head pressure 350 to 430 less than a min....... then back....I inherited this job.... low 75 to 90
Submitted: 2 years ago.
Category: HVAC
Expert:  airheatman replied 2 years ago.
Hello. My name is ***** ***** I'll do my best to help. Let's get started and see what we can do.Is this an R22 unit? Do you have model number?
Customer: replied 2 years ago.
Yes 22.......out of town on family issue..... did not bring my book.......
Customer: replied 2 years ago.
10 ton package heat pump.....8 to ten years..
Expert:  airheatman replied 2 years ago.
OK if the head is skyrocketing like this and outdoor fan is moving sufficient air across coil, sounds like a restriction such as a metering device or drier. Normally we will get a low suction though.Does suction drop any? THis sounds like a metering device TXV
Expert:  airheatman replied 2 years ago.
Also have you tried reversing from heat to cool modes to see if we have same behaviour?
Customer: replied 2 years ago.
Very hot and lonely...... is anybody out there
Expert:  airheatman replied 2 years ago.
I am not able to take call right now.
I have opted out of the question to see if perhaps other experts may have more information and can assist.Please do not rate or reply as that will send question back to my desk.Please stand by to see if another expert can assist further.
Expert:  Brian HVAC Guy replied 2 years ago.
Hi I'm Brian and I'm here to help. Sorry for the delay. A commonly overlooked problem with these package units is the condenser coil on some of them are split into two slabs. A two row deep condenser coil that actually is two coil slabs connected at one end (the manifold end where the hot gas and liquid connection is) and zip tied or screwed together at the other end where there are only vertical u-bends. The condenser coil can look absolutely clean even if you've cleaned it from both sides but the split between the two coil slabs can still be full of fine debris (cottonwood trees are famous for clogging these). If you take all the screws out of the three sides of the top around the condenser coil, you can usually lift the top up high enough so it doesn't contact the top of the condenser coil and prop it up with a 2x4 or the like. Next you have to remove the screws from the sheet metal cabinet where they attach to the tube sheet on the u-bend only end. Next, cut the zip ties (or possibly remove screws a few small brackets) that hold the two sheet metal tube sheets together. Then you can lift the whole condenser coil carefully up higher than the bot***** *****p of the bottom pan and carefully split the two coil slabs apart enough to spray down the inside faces of them both. Give that a shot and let me know what you find.Thanks, -Brian
Customer: replied 2 years ago.
ok.....430 am Monday....... can understand the condenser issue..... but how the spike
Expert:  Brian HVAC Guy replied 2 years ago.
I don't really understand what you mean by "430 am Monday". It's hard to say what the exact cause of the high head pressure then the sudden spike is but I would cover the bases first by looking at the condenser coil. If you lift the top and can see they are in two separate slabs, the chances are good it's the coil dirty internally between slabs. If the condenser coil was plugged between slabs you could have those symptoms if the compressor's internal relief was blowing off then closing back down. Sometimes the compressor and fan(s) is too noisy to hear the rush of gas across the relief. Noncondensables (air or nitrogen) in the system can also cause these kinds of high and wildly fluctuating pressures. I would start with examining the coil first though. Rule out the things you can visually see before recovering the refrigerant and evacuating and recharging with virgin refrigerant. Both problems can give the same symptoms. If it were a stuck txv, clogged metering piston or clogged liquid line drier, you would have a cooler than normal liquid line temperature and a way lower suction pressure. If it's caused by either of the first two problems above, the liquid line will be extremely hot with both problems. -Brian
Customer: replied 2 years ago.
thank you for some smart advise... that is rare.....
Expert:  Brian HVAC Guy replied 2 years ago.
You're very welcome. I know how it feels to be alone and in the trenches out there! Let me know if I can help further. Feel free to follow up and let me know how it goes. Thanks, -Brian
Customer: replied 2 years ago.
430 am.......comerical job on a hot roof........ and 5 fire breaks along the way.......30'building.....
Expert:  Brian HVAC Guy replied 2 years ago.
Oh man, I feel for you! I've been there (and wondering why the heck I do this for a living!). I can't anymore thanks to jobs like that! Be safe out there! -Brian