A/C Intermittent


#1

I have a 7 yo Honda with an intermittent A/C problem.



Sometimes when I start the car and turn the AC on, it works fine for hours.



Sometimes when I start the car and turn the AC on, it blows HOT air on me. (So hot, it actually makes opening the windows to Atlanta’s 95 deg/85 % humidity seem cool)



There seems to be no rhyme or reason to this, it will blow cold at 3:00 during the hottest part of the day for an hour. I’ll make a 5 minute stop at a convenience store, get back in the car and have it blow hot on me. I’m starting to leave it running (with my BIG dog in it) just to have it keep blowing cool.



This is not a recharge/add coolant issue, as I already had a garage try that and it didn’t help.



Thoughts? Thanks

Maureen


#2

There is probably a problem in the control side circuit. An intermittent problem with a component such as the low pressure switch.

The best thing to do is to have someone that specializes in A/C repair look at it when it is acting up.


#3

And if it’s a really intermittent problem, have the technician install a small fuse (rated for way less than the normal circuit current) in parallel with each suspect control. When a control opens, the current tries to flow through the fuse and blows it. The fuses can then be measured and the problem control located.


#4

thanks for the suggestions.
i’m just worried about cost at this point.
the garage that did the recharge wants $100 just to look at it again. other garages are saying the same thing.

guess i’ll just have to suck it up and pay it. either that or sweat a lot off and on :slight_smile:


#5

I don’t see where the problem is blowing fuses.So what the heck are you talking about?


#6

It’s a practice used to make intermittent controls leave behind evidence. A fuse (or fusible resistor) is installed in parallel with each suspect control. The equipment is then operated until a control opens. The control that opens will direct current through the fuse, which is way undersized so it blows. Then the blown fuse is found and it points right to the control that was in parallel.


#7

Willey

“You’re entering another dimension, a dimension not only of sight and sound but of the mind; a journey into a wondrous land whose only boundaries are that of imagination. Next stop - Star’s posts.”

Can you believe this carp just keeps being perpetuated.


#8

If you think about it, consider if a control in a circuit has 1A (for example) flowing through it. There’s a 250mA fuse added in parallel. If the control is closed, little current should flow through the fuse (small fuses actually have surprising amounts of resistance). But if it opens, the current can no longer flow through the control. The current takes an alternate path through the fuse. 1A through the 250mA fuse blows it, making a permanent trace of what happened.

There are actually “control flags” that are used to troubleshoot control circuits.
http://www.johnstonesupply.com/corp/tabid/1783/default.aspx?product_group=1372
http://www.uri.com/is-bin/INTERSHOP.enfinity/WFS/PrcTransaction/en_US/-/USD/ViewCatalog-Browse;sid=-ZUx8EjyWYI18g5x4cg1RynNinMDCzsUy24=?CatalogCategoryID=4qWsEEGSqQIAAAESEkKqgJtk&OnlineFlag=1


#9

Wow, I can’t believe the stuff he says and the moderator lets it go. I keep flagging his posts that are way off base but nothing ever happens.

What he doesn’t understand in this case is that there are not that many control components. When the compressor stops working all you have to do is back probe the circuit and find the open circuit.

There is no need to waste time installing fuses in parallel. It is not a time saving method, in fact it is a time wasting method. This method might work in what ever world star is from but not in a automotive application.

What does it take for a modeator to act??


#10

Off base? They’re off the planet!
I have no idea why in the world he keeps making a potentially easy problem a major one with a lot of faux technical talk.

It’s just confusing someone who may know nothing or little about A/C problems.

If Star wants one to diagnose I’ll give him one. The A/C on one of my daughter’s cars was working great with no problems and all of a sudden just quit with only a very weak “cheep” sound. It’s not a blown fuse or a bad clutch coil.
Wanna take a stab at it? :wink:


#11

When the A/C is turned on, does the compressor have voltage at its terminals? Does it sound like it’s working?
Does the condenser fan spin?
Does the evaporator fan spin?
What are the pressures?
If the thermostat is digital, does the display light up? If analog, do the lights (if any) turn on?
Are you sure you checked all the HVAC system fuses?
Does the compressor relay (contactor) pull in?


#12

I just wanted to see what your response would be. Offbase again.
The entire clutch assembly and compressor end plate, along with all of the bolt heads, moved out 3/8".
It’s junk.