Maintenance & Restoration

GaryG · 07-14-2015, 08:05 PM

Eric, Got the ac in and running! Yeah, finally. It seems to be doing ok. Running a 2 hr. Test now. Still have a couple of questions though. Does the top of your bench get warm where the compressor is? Mine does. I would imagine that's normal. Also I used a 3" marine bilge blower in mine. Also used a pwm 12v motor controller which allows me to go from off to full on. The blowers sure are noisy on Full on. Trying to find the lowest position and still have the ac exhaust be efficient. Will get back to you with results. Thanks for all your help, couldn't and wouldn't have done it without your valuable assistance!

ericw · 07-15-2015, 06:24 AM

Quote:

Originally Posted by GaryG

Eric, Got the ac in and running! Yeah, finally. It seems to be doing ok. Running a 2 hr. Test now. Still have a couple of questions though. Does the top of your bench get warm where the compressor is? Mine does. I would imagine that's normal. Also I used a 3" marine bilge blower in mine. Also used a pwm 12v motor controller which allows me to go from off to full on. The blowers sure are noisy on Full on. Trying to find the lowest position and still have the ac exhaust be efficient. Will get back to you with results. Thanks for all your help, couldn't and wouldn't have done it without your valuable assistance!

Congratulations!

I have never checked if it gets warm on the top of the bench. I would think some warmth is not untypical since you have a heater below it. I usually have the cushions there. I know I have it so that outside cool air comes in the top of the AC and out the back, but there is not a lot of room on top.

A reminder that you probably already took care of. If your cabinet is not well sealed, you are sucking cold air from inside the scamp through the AC and out of the trailer (rather than using outside air to cool the AC) so your AC would be working harder. I had to add all kinds of weather stripping to make sure it was reasonably sealed.

I slowed my 4" marine blower down also for noise, but I just used heavy duty power resistors and not a motor controller. Nice improvement.

I can't wait to hear the rest of your results. Good work!

Eric

Darral T. · 07-15-2015, 09:18 AM

My Atwood 6 gal waterheater is underneath one of my benches. It has apx 1" styrofoam insulation on it and you can feel the bench get warm. The fiberglass is thin in that area. Nearly 6 yrs and it hasnt hurt anything. Just as long as your ac is getting enough air, I think you have a perfect self-installed setup.

[QUOTE=GaryG;534931] Does the top of your bench get warm where the compressor is? Mine does. I would imagine that's normal.

GaryG · 07-18-2015, 07:38 PM

Eric, i've got an issue. Ac runs blowing cool air for about 10 mins and then starts blowing warm air. Brand new unit. I thought it wasn't getting enough outside air so I stuck a 35 cfm computer fan on the intake hole. Still doing the same thing. It's 85 degrees an d 45% humidity here, so I don't think it's too hot or too humid. Also my unit is a remote control unit, but, I don't think that matters. I'm about to pull it out and stick it in a window to see if it's my installation or the unit itself. Any thoughts on this? Thanks, Gary

Sid · 07-18-2015, 09:29 PM

Eric
Do you think you could help this guy?

Darral T. · 07-18-2015, 09:50 PM

I'm not Eric, but if that A/C works ok in your window, it's NOT getting enough air to cool the compressor and it's shutting itself off to keep it from self-destructing. What size computer fan is that (in MM)? Sounds VERY small. You may as well get ready to multiply your CFM's by at LEAST 5-10!

If you have the air dammed up behind that small fan, that's your problem in my opinion. A/C's HAVE to breathe!

Quote:

Originally Posted by GaryG

Eric, i've got an issue. Ac runs blowing cool air for about 10 mins and then starts blowing warm air. Brand new unit. I thought it wasn't getting enough outside air so I stuck a 35 cfm computer fan on the intake hole. Still doing the same thing. It's 85 degrees an d 45% humidity here, so I don't think it's too hot or too humid. Also my unit is a remote control unit, but, I don't think that matters. I'm about to pull it out and stick it in a window to see if it's my installation or the unit itself. Any thoughts on this? Thanks, Gary

ericw · 07-19-2015, 06:03 AM

Quote:

Originally Posted by GaryG

Eric, i've got an issue. Ac runs blowing cool air for about 10 mins and then starts blowing warm air. Brand new unit. I thought it wasn't getting enough outside air so I stuck a 35 cfm computer fan on the intake hole. Still doing the same thing. It's 85 degrees an d 45% humidity here, so I don't think it's too hot or too humid. Also my unit is a remote control unit, but, I don't think that matters. I'm about to pull it out and stick it in a window to see if it's my installation or the unit itself. Any thoughts on this? Thanks, Gary

Gary, hopefully others will chime in with their thoughts as well. I will give a couple of my thoughts and I apologize up front if they are a little obvious, but sometimes those are the missing piece of information.

First, it could be that the AC thinks it is cool enough and turns off. I assume with the warm air you hear the compressor turn off. It could be working normally. We had this when we didn't have a fan redistributing the air in the trailer. It would get cold by the floor and then stop running even though it was hot at the top of the trailer. Your AC may have different modes as well (low, high, max, no energy saver...?) and that may effect things as well.

Second, the compressor could be overheating and shutting down. It could be due to something like the temperature sensor touching the coils, coils icing, or the AC wanting to check room temperature, but most likely it is due to lack of air flow.

Third, (similar to second) another guess is that you didn't seal well enough around the lower cabinet the AC sits in and trailer air is being sucked through the AC so hot air from the outside comes in the trailer making the AC work all the harder and causing a compressor shut down.

Before you take it out, I would try and check the amount of flow of air going in and out and the temperature of the air going in and out. (A battery operated remote temperature sensor is best but your hand is better than nothing. While you are at it, check the actual temperature in the air flow out of the AC and at the top of the trailer. Actual numbers help people on the forum since "warm" is a pretty vague concept.) The air flow/temperature check should also catch obvious issues, like if you have the flapper valves installed backwards blocking air flow in or out. The air on the exhaust should be pretty warm/hot and feel like a lot of air. Remember you usually have a couple of square feet of air flow on the back of the AC and now we have to get the same amount of air through a small hole. Make sure your blower is on high speed.

I agree with taking it out and seeing how it runs. If it runs fine, while it is out you might cover up a good portion of the back and see if it duplicates your problem indicating lack of air flow.

I did use a 4" blower instead of 3" which is ~75% more area and a bigger fan so that is my first guess. (even though I thought a 4" fan was overkill)

Totally unrelated, while it is out, make sure water is coming out the AC only where you want it to be coming out. You can just run this in your drive way. I just put it on a couple of saw horses so I could see what the water is doing.

Good luck and let us know what you find.

Eric

GaryG · 07-19-2015, 05:30 PM

Well tried a fan with more airflow on intake, didn't work. Took ac out and tried in window.Worked fine. Let it run on high for 90 minutes. Checked air temp on top of case over compressor. It was cool. While unit is in Scamp, it gets pretty warm at same location. I'm guessing the compressor is overheating and shutting down. But the intake fan I used seems to blow alot of air. I always run exhaust fan on high. How can I fix this? Drill another vent hole for intake air? Could it be the exhaust? I'm using a 3 inch marine blower. I'm done for the day.
Trying to get this fixed b4 vacation, Aug. 6. Thanks everyone for all your help!

ericw · 07-19-2015, 07:06 PM

Quote:

Originally Posted by GaryG

Well tried a fan with more airflow on intake, didn't work. Took ac out and tried in window.Worked fine. Let it run on high for 90 minutes. Checked air temp on top of case over compressor. It was cool. While unit is in Scamp, it gets pretty warm at same location. I'm guessing the compressor is overheating and shutting down. But the intake fan I used seems to blow alot of air. I always run exhaust fan on high. How can I fix this? Drill another vent hole for intake air? Could it be the exhaust? I'm using a 3 inch marine blower. I'm done for the day.
Trying to get this fixed b4 vacation, Aug. 6. Thanks everyone for all your help!

Gary, I hope others chime in as well. My best guess is an air flow issue. I use a 4" Rule blower at 235 cfm and their 3" blower is 135 cfm which is a sizeable difference. My exhaust is also reasonably warm and notably above outside temperature.

I think you need more air coming in and going out. (no use just having it go just in or just out ). So if you go 4" fan on the exhaust, have at least a 4" hole on the intake. Two 3" holes would be another option.

As I mentioned above, remember to seal well around the lower cabinet the AC sits in. That is another reason besides simple air flow from intake to exhaust that could cause the compressor to work hard. Let me know if this doesn't make sense.

Good luck. You are close.

GaryG · 07-19-2015, 10:43 PM

Thanks. I've got one more thing to try b4 I go 4 inch. My ehaust vent cover has stationary baffles, which might be restricting the air flow. I'll take it off tomorrow and see what that does. I'll keep you posted.

GaryG · 07-19-2015, 10:44 PM

I meant louvers.

ericw · 07-20-2015, 06:43 AM

If it isn't too much to ask, we love pictures (and it may all of us give you better feedback also).

Good luck.

Darral T. · 07-20-2015, 07:55 AM

I agree 100% with Eric. Pictures still speak "a thousand words".

I'm still leaning towards the fact that something is wrong with the "compartment" in which the back portion of the A/C resides. It "appears" that regardless of the fan, someway, it's recycling the hot air that's coming out of the a/c.

Just remember, warm air still rises. You say it's getting hot at the top. THAT is where you need to cool in my opinion. Again, it just appears hot air is being trapped in the compartment and allowing the AC to recycle it. As it recycles, naturally it's going to get warmer to hotter and that's when your compressor says enough.

Interesting stuff...wish I was there to help you troubleshoot! I love challenges.

GaryG · 07-20-2015, 09:42 PM

How do I post pictures please

ericw · 07-21-2015, 03:49 AM

Quote:

Originally Posted by GaryG

How do I post pictures please

It is not too bad after you have done it a couple of times

. Here is an old post explaining it. http://www.fiberglassrv.com/forums/f...tml#post217275

Alternatively, if that seems overwhelming, I will pm you my private email and I will post them for you.