# Ruud Acheiver 90 Gas Furnace



## harley101 (Nov 13, 2008)

There should be a small sight window with a clear plastic cover that will let you see a flashing LED indicating a fault code. You may need to remove the outer cover exposing the inducer motor and gas valve. 
If tou have a flashing LED, count the number of flashes and then you will likely need to remove the inner cover exposing the blower motor. There is a safety switch that will not allow the furnace to fire when you remove this inner cover. Usually on the back of this cover is a schematic and notes that will tell you what fault code you have.


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## 32FordCoupe (Nov 13, 2008)

*Ruud acheive 90 gas furnace*

Thanks Harley for a reply.The site glass is only on the burner end to see the flame.The other cover is solid.The codes i will have to hold the switch to see if there is one.I no that it has a grren light on when it starts and then when it goes off it turns amber.Im not sure if mine is new enough to have the codes?Made in 97 and installed in 98.I will take a lookat it this evening and get back.Thanks for the info


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## kennzz05 (Nov 11, 2008)

:winkut a piece of tape over the door switch to hold it in than replace the door when the furnace starts throwing a code you can remove the door to count the flashes if i had to guess its going off on limit ,all your return grills clean no furniture in front of them curtains getting sucked into them etc(if therelow returns) any chance its been operating this way for awhile and you just never noticed it? if it is the limit try running it with the door off see if that cures it if so you need to look into why you dont have enough return air (dont run without door indefinitly DUH)


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## 32FordCoupe (Nov 13, 2008)

Kennzz
Thanks.I removed the blower door and ran the thermostat up 5 degrees,taped the switch and it ran continuos until it got the the desired temp(no prob)There are 2 green lights on and when it ignited the amber light came on.When the flame went out the amber light went off and the 2 green lights stayed onThe green lights stay on anytime the switch is pushd in.Amber only comes on when it ignites.I replaced the door and let the house cool down and ran the thermostat up 2 degrees and it started the 60 sec off cycle again in the heating process.The return is in the ceiling with nothing to block or cover it.I have the electrostatic washable filters.(Got them when the unit was installed 10 years ago)could both filters be the problem?I also noticed that the blower fan has a little dust built up on it,could that be it?Or could the fan be just not turning fast enough?Not one of the techs that came here said anything about fan speed.Let me know what you guys think?Any help is worth a ton


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## harley101 (Nov 13, 2008)

OK, Replace the furnace cover as normal, then try removing the filters and use some cardboard or something to temporarally block any openings so the furnace gets a good draw thru the return duct. 
Try setting your t-stat up 5 degrees ad see if it will run a heat cycle without quitting. 

If it cycles as it should, your filters are the problem.

If it is still cycling after 60 seconds you are not getting any draw thru your returns


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## beenthere (Oct 11, 2008)

Probably a combination, of the air filters, and a dirty A/C coil(if it has one) tripping the high limit due to low air flow.


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## 32FordCoupe (Nov 13, 2008)

Harley, Kennzz and Beenthere
I removed the filter,ran the t stat 5 degrees and it ran perfectly with no problems.It does have a a/c coil and i looked at it on monday(still in the case) and it wasnt a bit dirty.I didnt see any dirt on it what so ever.I could only see about 75 percent of it but what i did see was very clean.What kind of filters do you guys reccoment as that seems to be the problem?It is 20 x20 sized in the ceiling.


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## 32FordCoupe (Nov 13, 2008)

Well after thinking about this,i cant see where the filter could be the problem.The filters are as clean as the day we bought them.I think what might be happening is without the filter there is enough air flowing thru the system and with the filter in it cuts the air back letting it get to hot and setting off a weak high limit switch.What do you guys think about that senerio?


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## beenthere (Oct 11, 2008)

Limits only get weak if they have been close to their trip temp too long or too often.

So you still have an under lying problem that cause the limit to weaken.

As clean as the day you bought them? How long ago was that.

Is the secondary HX clean.


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## 32FordCoupe (Nov 13, 2008)

Beenthere
What im trying to say is that there isnt any dirt or dust on the filters.If i were to buy new ones they would look exactly the same.They are the ones you spray out once a month.I have 2 or them and i alternate between them.The hx i havent seen to know if it was clean.From looking into the blower end of the furnace its almost spotless,very light dust if any.Could the hx be bad causing this problem?I had one time last year where i let the filter go too long in the winter before i changed it,can that cause the problem?Seems to me that was about the time this issue started.Let me know what you think the next thing to try or look at is?


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## beenthere (Oct 11, 2008)

A bad HX can cause this.

To see if teh secondary is dirtly, you have to pull the blower. The secondary looks like a car radiator.

Guessing your using electostatic air filters.

One of the worst types you can use, unless your duct work was designed for them.

Also, electrocstatic filters, don't show how much dirt they may have trapped inside of them.

You just spray them off?
Yoiu need to use a good cleaner on them, or they won't release teh dirt that they have trapped inside of them.
Simple green works great on them.


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## 32FordCoupe (Nov 13, 2008)

what are some symtoms of a bad hx that i can look for?How can i tell if the hx is bad?


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## 32FordCoupe (Nov 13, 2008)

when the tech installed the system(complete duct and all) this is what he reccomended for filters.


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## beenthere (Oct 11, 2008)

32FordCoupe said:


> what are some symtoms of a bad hx that i can look for?How can i tell if the hx is bad?


A visual inspection of the HX.


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## beenthere (Oct 11, 2008)

32FordCoupe said:


> when the tech installed the system(complete duct and all) this is what he reccomended for filters.


I doubt he checked to see what the static is of your system with those filters.


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## kennzz05 (Nov 11, 2008)

electrostatic and pleated although being efficeint are real pains in the ass from most techs point of view they do cause issues with constricted airflow its likely your furnace has been doing this for some time,perhaps with less frequency until now


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## 32FordCoupe (Nov 13, 2008)

no i dont think he did.You are right.I have the blower out of the unit and i can see that the heater core (HX)looks like it really clean.All nice and clean.I did however find upon pulling the blower out that there is insulation glued around the cabinet (inside)and a pc of that had fallen down on top of the blower.I will take some pictures and see if i can post them for you to look at and let me know what you think?


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## 32FordCoupe (Nov 13, 2008)

what do you recommend as for putting great filter system in or filter?


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## kennzz05 (Nov 11, 2008)

GLUE THAT INSULATION BACK or simply pull it out could it possibly be sucked in the fan?? and reduce the airflow? that may be part of your problem but i forgot removeing the filter helped so prob. not. filter reccom. 1 in pleated if you gotta have a real good filter and change it at least 4 times a year more if you have kids/animals


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## 32FordCoupe (Nov 13, 2008)

Kennzz,
I glued the insulation back.It was laying flat on the top of the fan so i suppose it was only drawing on the bottom side of the fan.It could have been restricting enough airflow to break the limit switch and when the filter was out maybe it added enough to let it work?I have some pictures for you guys to look at.Let me know how to upload them here?


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## 32FordCoupe (Nov 13, 2008)

Lets see if these pictures will work


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## beenthere (Oct 11, 2008)

You can use a general(purpose) pleated filter. They are good but not to restrictive.
Not the 3M filtrete.


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## kennzz05 (Nov 11, 2008)

you might look into making sure your fan is on one of the higher speeds too usually done by switching them around on the circuit board use the diagram to identify the speeds


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## beenthere (Oct 11, 2008)

Its not that bad, but its not as clean as you might think.
The dirt you see on the insulation, is also in between the fins of the secondary.


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## 32FordCoupe (Nov 13, 2008)

Thanks for the help fellows.I hope we can get it figured out.I guess the fan could have slowed down as it has been on the same speed for 10 years now.I figure i have a different issue and would like to find the problem before i change anything.I found the insulation on top of the blower wheel,and havent tried it yey since this.I can try another filter in it or try it like it is and see what it will do?I had very little dirt on the insulation and had very little bit on the blower wheel,which i cleaned and vacuumed out today.I think the secondary is pretty clean for 10 years?Let me know what you guys think i should do from here
Regards
Rick


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## kennzz05 (Nov 11, 2008)

the secondary is certainly clean enough to not warrant yanking it to clean it speeding the fan up can compensate for the restrictive filter. on the rating plate there is a rating for the range of differance between entering air and leaving air i think is listed as temp rise for instance if it says temp rise-45-75 and your entering(return) air temp is 70 degrees you should be looking for between 115- 145 degree supply air below that your moving too much air, above that not enough let the furnace run long enough for the temps to stabilize


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## 32FordCoupe (Nov 13, 2008)

Kennzz and beenthere
I tried it this morning 1 time.Ran the temp up to 75 from 70 and it turned on and ran the whole time without an issue.It took forever to get up to temp(over 1 hr)Low pressure coming from the vents.I removed the filter while it was running and the pressure came back like it was new or first installed.I think its going to be the filters?Im going to install one of the pleated filters as you guys reccommened.So looks like it might be 2 bad electrostatic filters?


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## beenthere (Oct 11, 2008)

Those filters don't release the dirt just using water to clean them.
Takes a soaking from a good cleaner.
I use simple green on them.

At this point though, it may be too late for your filters.


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## 32FordCoupe (Nov 13, 2008)

Alright Fellows
I think we have this one done and ready to move on to the next one.I have a garage attached to the house,it has insulated walls,ceiling and all is completely plastered.Garage doors are insulated as well(2 in thick)The size of it is 24x36x10 foot ceilings.I want to cool and heat this as well.Anyone want to make any suggestions as what would be the best setup to use here?Let me know what you guys think?


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## beenthere (Oct 11, 2008)

How arm, and how cool.


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## 32FordCoupe (Nov 13, 2008)

Just about like the house as i do alot of work in it.I want it to be comfortable.Let me know as i need to install everything in the attic.I already have some insulated metal trunk line there with flex from it to 3 round 8 in vents running down the center on the 36 foot lenghth.


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## beenthere (Oct 11, 2008)

Probably 1.5 to 2 ton heat pump.


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